You were looking at either an X748 or an X749 Ultimate tractor. The 748 lists for $12,500 with a 54" deck and is 4WD and the 749 lists for $13,500 and has 4WD and 4WS. Both are true tractors capable of powering and pulling ground engaging implements/accessories and you should see the massive axles and transmissions on these machines when the wheels are off !
I bought an X729 last Fall when Deere was offering a nice rebate and it has a 27 HP Kawasaki V-twin liquid cooled gas engine, 4WD and 4WS. I didn't see the need in my application for the extra expense and hassle of a diesel.
I'm able to access parts of my property with the X729 that I couldn't come close to with my old Cub GT3100 and with the 4WS can trim right around trees, landscaping etc. without the steering issues of a zero-turn mower and all the unique problems they can present.
At my better-half's suggestion I also got a 54" snow blade with the tractor and the ease of removing the 54" mower deck and installing the hydraulically controlled blade and vice versa is well thought out and completely tool free. This past Winter that blade paid for itself several times over clearing mine and a couple of my neighbor's drives. All in all a truly awesome machine and a pretty good example of getting what you pay for, IMHO.