You're not going to get very far trying to game on a college budget if you don't know the places to check religously for deals. All the outlets below are ingrained in my mind and they should in yours as well, young padawan
CheapassGamer is the holy grail for those of us trying to game on the cheap. I can't even begin to talk about how much this website has benefited me. Of every resource I list here, this is by far the most important. It should be noted that the hompage of the website isn't updated anywhere near enough to be useful. Simply sign up for their forums and check the deals section everyday. You'll thank me later.
Slickdeals is a website similar to Cheapassgamer. You should register for their forums and check the deals section at least once a day. The problem with Slickdeals is that it isn't only dedicated to video games, which can cause finding the gaming deals to be a hassle. However, the site stil finds some deals before cheapssgamer does and is worth dealing with for that reason.
Steam is seen as the beacon of light in a fading video game industry right now. The platform has deals constantly and you can quickly amass a collection of hundreds of games at prices that seem unbelievable. Steam is unfortunately relegated to PC gamers, though make note that it also has Mac and Linux games, only. So, if you're not a PC gamer then you're kind of out of luck here. If you are a PC gamer than chances are you know about Steam already, but it's important to note just how frequently they have sales. It's honestly pretty mindblowing just how often it happens. And because I can't resist a good deal, I have more than 100 games sitting in my Steam backlog currently...
Amazon is one that I'm pretty sure everyone reading this knows about already. Amazon is a lifeline for many a college student in a variety of matters and it's no different when it comes to video games. Amazon frequently has a plethora of deals, and they also frequently have games a bit cheaper than the competition - even if it's only by a couple bucks, and free shipping for orders over $20 never hurts either.
GOG is a service similar to Amazon. They sell a variety of computer games for PC and Mac. GOG mostly sells the classics, many of which are not available on Steam at all, at very cheap prices. Revered titles like Fallout, Fallout 2, Planescape: Torment, The Longest Journey and more are all available on GOG for under 10 dollars. That's a pretty cheap price to pay for the amount of gameplay those games can provide. If you're a PC gamer, definitely give GOG a try.
That's all the for the list of resources. I hope they aid you as well as they have me. I should state once more, however, that Cheapassgamer is the main point to take away from this page. All the other resources are handy but Cheapassgamer can lead you to them just as well.