Agreed with the above that big will be a nightmare to heat and offer proper gradient, glass is not the best insulator, a PVC cage however will be. Not to mention if you want to go with a tank a 40 gallons breeder will be enough even for a female.

There are plenty of reptile supply vendor at repticon and usually prices are much cheaper than your average pet store, for example the cages I have bought were $80 versus $120/$130 in pet stores.