How to Find Cheap Retro Games

Retro gaming can be an expensive hobby if you're not careful. The main reasoning for this is because it has become mainstream in recent years, which is both good and bad.
I don't want to come out as a Hipster twat or anything (too late?) but the bad side is that it makes the demand for the product go up. Since retro games aren't manufactured anymore, the demand is going up but the amount of product out there is staying the same. This is making the prices go up, which is understandable, but lame for us collectors at the same time. It's great that it's getting more recognition now than it ever was, which is the good since it deserves to be more appreciated but it does sting the wallet.

But hey, don't cry. There are ways around this, which I've figured out over three years of collecting.
I'm by no means a pro or anything, but I've done this long enough to know where to look, and damn it, it works for me. Hopefully it will work for you too.

Op Shops
Otherwise known as thrift stores. You know, the ones Macklemore told you to go to? I never really went to these until recently, which was a big mistake on my behalf as op shops are the motherflipping boss.
You see, these are not always going to have stock, that's one thing I've figured out. Many times I've gone into one, and come out empty handed except for a $4 wooden South Park poster.

True Story

When they do have stock though, the prices are excellent. Not to discredit the fine volunteers of op shops or anything, but most are old woman who don't have a single clue about gaming. They're in the same generation that consider games "toys for kids", which I usually hate, but since they're of that opinion they price them quite cheaply. Most items are under $5, no matter what it is.
When it comes to games that are in CD or DVD cases too, they're usually just lumped in with the actual CD's and DVD's, which are mostly priced at a flat rate. The only downside is that you have to hunt through copies of Hanson's Greatest Hits and the complete season third season of Neighbours on DVD, but some weirdo's like me find that fun.
I also recommend checking out the board game sections, as big boxed PC games tend to end up there. Sometimes, they're lumped in with actual kids toys too if the employee thinks they're just for kids like I was explaining before. The other day I was in a Salvation Army and next to some McDonald's Happy Meal toys was a PSone for $13 that had a copy of Rugrats inside, and a SNES racing game for $3.
It a pays to look, is all I'm saying.

Swap Meets
Otherwise known as Flee Markets, these are the places of choice if you want to pick up some 1980's romance novels or pot plants, but people sell their old games too.
Sadly, with the invention of the internet and then smart phones with 3G/4G access there are a lot of sellers who base they're pricing off eBay. This is the sort of thing we want to avoid really, but it does (again) pay to look. Every now and again you'll hit a jackpot, whether it's someone who just wants to get rid of their 'junk' no matter what or clueless mothers clearing out their attic, there are bargains to be found.
I haven't been to many as of late, but recently I scored a $5 copy of Grim Fandango which I was quite proud of.

Garage Sales
These are where people sell their old possessions in their yard, so quite like swap meets although you have to hunt these out more.
Again, these can be hit and miss since a lot of people check their prices online these days, but it's always worth a look. You never know, the seller might be willing to haggle.

Pawn Shops
Pawn stores are a double edged sword. On one hand, they always have good stock, but on another these were the guys who pioneered online price checking. Again, these guys might be willing to haggle but it depends on the circumstance. Usually if you buy a few items they'll be willing to bundle them for a better deal.
Like all retail environments though, they have sales and constantly change the price of their stock. If something sits there for a while, they may bring down the price to clear it out. There are a few places I always check out, and it seems the prices change every visit.

Dedicated Retro Stores
This may not apply to everyone since these aren't everywhere, but there are stores out there who's sole purpose is to sell retro video games. Of course it can vary from store to store, but these places are always very competitively priced , with the staff being highly knowledgeable. Since they deal in the business of games too, usually the consoles are on hand so the games will be tested. These places may charge more, but unlike pawn stores it's always very much worth it.

Craigslist Sorta Websites
These are basically online swap meets, the digital version of the classified section of a newspaper. These can vary depending on where you are; Craigslist is the big one in America but in Australia Gumtree is more popular. This can be a mindfield to navigate as I've talked about plenty of times before, but the deals are there. You just have to find them.
The best luck I've found was with game lots, people will sell a bulk lot of games for a discount as opposed to selling them individually. Sure they may make more with individual listings, but luckily for us most people are lazy.
Some of my best scores include a $20 Mega Drive and a $10 Atari ST.

Emulators
Emulating is where (using software) the games can be played on the computer, and are downloaded from the internet. This is the cheapest option, as it's obviously free to do so. It is a legal grey area however, since you're technically pirating copyrighted material, and you're not playing on real hardware so it isn't really the same.
However, if don't mind the risk of being sued and don't actually want to collect and pay money but just want to play the games, emulation is a great road to take.
Be warned though, emulators don't always display the game properly and playing console games with a keyboard and mouse is balls. You can however buy adapters that let you plug real controllers in via USB. These can be found on eBay usually.

Officially Emulated
The other option is to buy the official ports, which while more honest also usually guarantees a better experience. This is because since it's the real deal, the controller mapping has been redone making them quite easy to pick up and play.
These can be purchased from the PSN, the XBLA, the Wii's shop (which can be used on the 3DS also) as well as online stores such as Steam or GOG.
There are also retail versions of collections floating around such as the SEGA Mega Drive Ultimate Collection on the PS3, which I reviewed not too long ago.

When they are Cheap
This is just sort of a general thing, but worth noting none the less. After a console is discontinued, but before it's generally considered 'retro', the pricing of the hardware and the games are ridiculously cheap. This is during a time when no one cares about them, so it's the best time to pick up some fantastic games at some even better prices. Just check out one of my most recent posts about my collection and check out the PS2 section. Most of the games I've picked up in the last year and a lot which were under three or four dollars. The same thing is happening with the original Xbox too.
With the Xbox One and the PS4 just being released, expect the prices for the PS3 and the Xbox 360 to plummet more than they already have in recent years. At the moment it's not out of the ordinary to find them under $20 each, and they're not even discontinued yet.