my friend picked up a martin for 750 used and it is very nice, it sounds great, plays great, and has plenty of projection. I will ask him what model it is.
i've got a taylor big baby and a takamine g 10. the taylor plays and sounds better. i also checked out a hofner acoustic and thought it was good bang for the buck.
You would be surprised what you can find if you look. I found my 1990 Taylor 615 for $1000. They don't make them anymore. It is pretty much Taylor's J200. All maple, non cutaway jumbo. Used is usually the way to go.
I played a coue of those Martin x series a few months ago... loved the tone and playability... compared it to some higher end martins, Taylors, etc but there was something about them I really was digging and it walked all over everything at its price point...