The big difference between "electric" and "acoustic" amps is how they go about reproducing sound. Acoustic amplifiers are just more finely tuned to reproducing the tones an acoustic will generally make.

I think your best option (since you're playing an acoustic anyway) would be to save a little bit and get a 30-60 watt tube amp. If you shop around you can find a nice used one that will fit your needs. $150 practice amps sound like crap (I don't care who makes it) and you're going to want to enjoy the way that electric sounds when you get it right? Also, if you ever decide that you do want to jam with some other people or play out, you'll have enough power to get by.

At any rate, until you buy your electic you shouldn't need an amplifier so you might as well save your money now.