Here's what you do:) Buy a Yamaha FG700S... They are about 200 bucks and you can find some that sound great. Then spend $50 on a set up with some heavy strings (13's) and medium action (too low action feels great, but kills the tone)
Then you buy a L.R. Baggs M1 soundhole pick up ($170). They sound awesome and you can install it your self. Or you can have the guy that does the setup install it.
Total price: $420 for a good acoustic guitar that sounds good unplugged and plugged in.
This will sound pretty good through a P.A., and you can add a reverb pedal if you want something extra!
If you play with a loud band, you may get some feedback problems, but they can be fixed!
As far as acoustic amps go, I play a Phil Jones Acoustic Amp, and I love it. It's about $500 and sounds great. It's small, weighs good as nothing, runs on international power and looks cool. The Fishman Loudbox is great too, but it's a little more expensive.
Hope this helped you!
Anders