def be better just to go to a lfs. you can get a 5 or 10G for less than ten bucks at most good lfs's... not petsmart or petco... they mark everything up cause they use "namebrand" aquariums
A 5 gallon actually costs more than a 10 gallon, it is less common, and not a standard glass size, increasing production costs. If you are near the south side of Chicago pm me, I can usually dig up a 10 gallon from somewhere.