If you want to start collecting retro games, which seems to be all the rage these days, there are a few ways to get started. Here I will help you to learn how to get the best possible deal so you can easily build up a starter collection without breaking the bank.
Select a retro system you want to collect for, or you can have multiple choices. The first step is to get the console so that you can play the games you collect. The best place to find consoles would be at retro gaming stores either online or off. Auction sites like eBay are great for this as well.
Find a list of all of the games that came out for each console you want to collect for. There are a few great websites that list all games that are out fo a system, like Gamefaqs. Just use the page in the reference section below this answer to find the page for the system, and then organize the game list in alphabetical order.
Once you know what games you need, you have to figure out where to buy them. My advice is to check eBay first. This is where you can find most games at any time of the year. Some are going to be rare and hard to find, but that's okay if you just make sure to check it regularly. Here are some terms that can help you to know what a game should be worth:
Factory Sealed - This means that the game hasn't been opened or played, and still is in its regular packaging. This is the most expensive option, but it also means that you are for sure getting something that will work and look great on your shelf.
Grade - There are grades for each game that eBay lets the seller set. They range from poor to new condition. This gives you an idea of what shape the game is in.
Description - This is where the seller puts in information that gives you a much better idea of what the game is like and what their seller policies are.
You should always look at completed listings when you are looking for a game on eBay. That way, you can go through and see what it has sold for over the past few months so that you don't accidentally hit Buy It Now and get a bad deal on a game because you didn't take a few seconds to price it.
Flea markets, thrift stores, and websites like Craigslist are other places to find deals on video games. Part of the fun is hunting for the games, but the best part is reliving your past and playing some of the best games for retro systems.
1 - http://www.gamefaqs.com/games/systems
2 - http://www.ebay.com/gds/Buying-Retro-Games-and-Consoles-on-eBay-/10000000000897062/g.html