In the lower 48 you should be able to buy used 5 gallon soda kegs that hold pressure for under $40 each.
You are going to need a CO2 regulator, you will have to buy one.
Before you buy a system, you need to figure out about getting CO2 into a CO2 tank. Generally the local to you place that does CO2 fills will be happy to sell you a used tank and then when it is empty you bring the empty tank and they trade you out a full one for a few bucks. You can buy an empty tank and pay for shipping, but you need to figure out how you are going to get it filled before you do that.
You are going to need some tubing and some hose clamps and some hose barbs and some threaded bits.
If you keep reading here you will find most of us use 10 feet of 3/16" inside diameter tubing from the beer out connector on the keg to the tap. Most of the online kits use shorter fatter tubes. For general run of the mill beers carbed from 10-15psi, 10 feet of 3/16" inside diameter tubing lets us store our kegs at serving pressure and we get a good pour without too much foam. It works good. Slow maybe, but good. You can get 20 feet of 3/16" ID tubing at Lowe's-Depot for about three dollars.
So two kegs, $80. regulator all you need is the single gage, the second gage is useless, call it $75. 5 lbs of CO@ ~$10. Tank to hold it in, unknown. Tubing and hose clamps from Lowe's-Depot $30.
Besides kegs you are going to need grey posts, black posts, taps and hose barbs from a HBS. I use the threaded posts with seperate hose barb and collar, about $10 per keg post, there is another $40-50.
So $250 plus a CO2 tank leaves you $300 for a dorm fridge and tap tower hardware.
You are in like Flynn. At my house I just stick a keg and the CO2 tank right in the main fridge with the rest of the food.