If you want new I would be looking at the JD 5103, 2007 or earlier model, hopefully on closeout for $13k or less. Basic 2wd with 9x3 gear transmission, about 44 PTO hp, 3 cylinder turbodiesel which is fairly efficient, should be perfect. Also, though a lot less common, the 5105 in a 2wd model would be very similar but is a slightly more powerful 3 cyl non-turbo engine, 47 PTO hp, and has an 8x4 gear transmission with a shuttle lever (combined with hi/lo range lever). Not sure what price would be - I don't think dealers ever ordered a 2wd 5105 when the 2wd-only 5103 was so cheap. Both use a 2.9L 3-cyl which I assume is basically the same architecture, but the 5105 despite being non-turbo makes more power than a 5103 and is a bit more efficient based on Nebraska test lab tests. Either one is going to be more efficient than most other tractors in that power range, based on reading those same tests for those and similar models from NH, CASE, Kubota (what few tests are available), etc. I have 95 hours on my 5105 (with MFWD and FEL) and it is an extremely solid, simple to use tractor, with amazingly low fuel consumption (approximately 1 gal/hr in my use, which has been somewhere between 1/3 and 1/2 mowing with a 6' cutter, and the rest a mix of FEL work and tillage with plow and disc; I haven't been thinking my use has been all that easy on it!).
Kubota MX5000 is also available in 2wd around that same price. It has comparable hp but a smaller 4-cyl engine that may be less fuel efficient. Definitely worth a look though. It is based on a prior L-series frame and is a bit smaller and lighter, which could be good or bad depending on your exact use.
