Going all-grain is the cheapest/funnest route in the long run IMHO. I too am a college kid, and can empathize with your budget. Personally though, I see homebrewing as a hobby and joy, not just a cheaper way to get me and my friends drunk. Ultimately, if you want the CHEAPEST route, go buy yourself 18 packs of keystone, miller, natty etc.
If you genuinely want to get into the hobby of homebrewing for the fun of it, do what I did, and slowly start buying bits and pieces to get a cheap all-grain system together. I searched craigslist found a sanke to brew in for $20, and was able to get my hands on a 10 gallon igloo to mash in. My parents were nice enough to give me their old turkey burner as well. I also built myself a cheap keezer as seen on my sig. No shame in doing on the cheap!
Clearly, in order to save up for my system, I had to compromise and miss out on the spring break trip to the beach, or the summer trip to Cancun, but I don't regret it one bit.
Now, if you really want to get good at the hobby, use that search bar up top, check out some brewing books (i.e. How to brew:
How to Brew - By John Palmer), or ask the folks here on HBT and they will be happy to answer and questions or doubt you have.
