Use to just have my bedroom with a 46 gallonbow front on a dresser lol wanted a 55 but couldn't afford it (got the bow for free). Moved out and live with my fiancee we now have a 15 gallon plant, 46 discus, and a 75 blackwater for my black ghost knife it'll get better!
Read over your rental agreement, check under your flooring or build your own stand. If you have the space even a 700lb tank can sit on a second story apartment floor. As for money.. where I live it's about $50 per square foot of tank by that I mean the light, 36" vs 48" or even sand/gravel. My 75 gallon vs our bowfront 46 gallon it's at most $200 difference total.
I got lucky and bought the 75 tank, stand, & canopy for $200 and that's only about depending on sale or not 40 - 80 more than the stand for the bowfront alone.
That said if you want bigger the price in my experience is worth it, small tanks can run a lot too