If you're looking for a practice/combo amp, those are fairly cheap, especially if you buy a second-hand one. Search "combo amp" on Musician's Friend and you'll find a good lot of amps in your price range with reviews to boot. If you're super cheap and not a sound snob, you can pick up a battery-powered Danelectro Honeytone mini amp for about $30. I personally have the headphones-only Dano amp, which is handy for traveling--I can just pack it into my guitar case and not have to lug around my unwieldy practice amp.