agreed, bigger is better in this case. also, dont just look in the major pet stores for aquariums. petsmarts near me sell 55 gallon tanks for $120. and guess what, i can go over to the lfs where an old friend of mine works at and they have 75 gallon tanks of the same or better quality for the same price, $120. so shop around.
a piece of advice, take this for what you deem it is worthy of.
i have heard it time and time again from ppl in this hobby that once someone has been bitten by the aquarium bug they will always be an aquari-ist. this quite possibly could be a life long hobby for you. through-out your life your tastes are libel to change and you may end up wanting different types of fish - fish that get over 6" even. because of this you should never get rid of your equipment, even if you take a break from it for a few years, this way when you start to remember the joy aquariums bring you will already have the materials to get things rolling again instead of having to repurchase all new equipment. so if you start off with a bigger tank right now it may work out for the best in years to come. hope this helps.