heyys.
from what i know. if you want a cheaper tank. its best to go for a nano tank. which is somehwere about under 15 gallons. the equipment used for this will be way cheaper.
of course though, this will limit you to your choices of fish and corals and othere livestock. and this is almost more challenging as there is less water and so the water will have to be absolutely fabulously cleaned and mantained well. this might take up more of your time. if your serious about this, this wont be a problem for you. but if not stick with the big tank and fishes deserve a good life too.
plu remember, dDONT overstock.