I've got two acoustic 12-strings:
A Martin J12-15:
http://www.mguitar.com/guitars/choos...z&g=n&m=J12-15
and an Aria AW75-T in black:
//www.ariausa.com/series/aw75/aw75.html
Obviously they're very different. I paid £800 for the Martin and £175 for the Aria. The Aria is VERY musical for such a cheap guitar, and if you're not a brand snob I would definitely recommend trying one out. Superb value for money. A very bright and jangly sound and my "take anywhere" strumming guitar. This guitar nails Wanted Dead or Alive by Bon Jovi perfectly.
The Martin is fantastic and has a really smokey, mellow tone due to the mahogany top. A really deep and full sound with a very smooth top end. A more subtle 12 string tone. It's great for songs like Wish You Were Here by
Pink Floyd and Hotel California by the Eagles.
You may think two 12-strings is excessive, but the difference in the guitars is so great I've kept both as they cover different ground musically. I'd try a few out in your price range, and even some above it, so you can see what suits you and the tone you're looking for.
Whatever you go for - you can't beat the sound of a good 12 string
