it all depends on how cheap you can find you're keg stuff - i bought mine of a friend at work that no longer used any of it so i got a great deal
the kegerator itself is only about half your cost, and thats if you only run one/two lines, if you're talkin about running a nice tower and such with two or more beers, the kegerator could cost you more than your CO2 canister & all the corny kegs you'd want, so - approximate $200 for a DIY kegerator with lines or alomst double that if you go and get a new(er) mini fridge.
I'd concentrate on the beer *making* equiptment first, a brew kit with primary and bottling bucket, hydrometer & maybe a secondary carboy. you can bottle with any bottles, you just need some caps from the store (though it can be a pain sanitizing enough bottles)
if you're really worried about space, just do a primary fermenter for now and build on it later - i do about 20 gallons a month here by myself in an apartment, but with no roomates its easy to spread out and make a mess for a while without repurcussions