Being in college, I'd recommend either a nano, or no tank at all, and just save up for one once your graduate. I started once I got out of college and it's a good thing. I didn't believe how expensive the hobby would get. Someone might say they spent $2,000 on a 60 gallon setup and I just didn't see how that was possible. I'd add up individual parts, and come up with something much less. But there's always livestock, live rock, sand, additives, snails and CUC, lighting, heating/cooling, Test Kits, "conveniences" like automatic top off or an apex...etc. The worst thing would be to get into the hobby, after spending all of your money setting up a nice tank, then when problems arise you have no money left to fix any issues that come up.
When your tank is set up it will have issues that you will have to try to fix. happens to every tank. Generally large water changes are suggested as a starting point, then testing from there which may lead to more equipment or more live rock or something. Often people hesitate to change out water as it can get pricy changing out a lot of saltwater. But at the same time, that's the cheapest part of the hobby, so if you can't do adequate water changes on your budget, than it's not a hobby you can really keep up with. Finances are a big downfall of this hobby.
On top of the finances you need to start up and keep running a tank, it also takes a lot of your time, which you likely don't have as a college kid (at least not if you're an engineer or something that takes up a lot of time). When it comes down to it, there will be lots of times when it's either study and do homework, or take care of the tank. Studying and doing well in school (IMO) should always win. However, that means your tank will suffer, which isn't fair to it's inhabitants.
If you really can't wait, I'd recommend a used nano from someone else who realized they don't have time or money for the hobby. Craigslist tanks can be had for pennies on the dallar if you search frequently and are patient.
