i hear that walmart sells a 20-25 gal tank too but i haven't had any personal experience with their aquatics department.
Wal-Mart's 29 gallon kit is $94. Comes with hood, bulbs, heater, Regent Filter, filter cartridge, thermometer, net...and more little things.
Other than that...check your newspaper in the classified ads. I know some people will see tanks for REALLY cheap. Look around, you'll be surprised at some deals you can find.
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