Hi!Elderly Instruments sells the Martin 000-15S for US$714 plus tax. The 2 that we played sounded quite good and the extra interior space allowed by the 12-fret body seemed to make a sunstantial difference over the 14-fret model.
I agree that Martin M or 0000 guitars are very versatile guitars and sound good as a rule. I have probably played 15 or so and only one of them was a dud. I've owned both an M-36 and an M-64. I still have the 64 and I use it for everything but bar gigs. It is loud, evenly toned, comfortable and, I feel, very inspiring because it's so attractive to look at. They sell for about US$1300 used.
I played a 00-17SO yesterday. There are 2 at Mandolin Bros right now. It is very loud for the size, very nicely finished and will be a great guitar down the road. It has a very "new" sound right now. The price tag said US$1700, I recall. I see that 00-17 is going to be a standard stock model that should sell for just about US$1000.
All the best,
Dan