I'd just point out that whatever it is, you'll probably want two of them so that you can record in stereo (I guess some mics come with two capsules for stereo recording, and so one of those would work, but I don't know much about them).
Anyway - not much to add in terms of SDC recommendations over what's already been posted. I have a pair of Marik-modded MXL 603s that I have yet to try out. Based on my other Marik-modded mic, I kind of expect them now to be better than any of my other mics for acoustic, but I suppose we'll see. I didn't like them stock, and I didn't like them very much after my initial capacitor mods. I like the SM81 (2 of them would be out of the price range, even used) and the MK-012 (2 of them might be in the range, used). I also like Naiants (I've got X-Q - well inside the price range for 2). I've got some AKG C451E mics (out of range) that I haven't done too much with yet - they seem a little bright for my acoustic, but maybe not with good placement -- all around nice sounding.
Outside of the SDCs, I like the AT4033 (2 used would be out of range) "medium" diaphragm condenser, and the AKG C414 B-ULS (out of range, unless you find a cheap used one like I did). I've got a fairly full complement of cheap (sub $200) LDCs, but I don't really like any of them on acoustic.