I have an 06 TC26DA, about 880 hours. It's a good tractor but the tranny case cracked on me a couple years ago, and that is one major expense to have replaced. Now I'm worried about it cracking again. The dealer said that that kind of thing seldom happens on tractors without hoes. I don't have a backhoe on mine, and I think it's generally been used pretty lightly. Before buying, get under the tractor and look for any oil drips, especially around the axles going into the transmission. Clean underneath and look carefully for tiny cracks. I don't think this is something that is endemic to this tractor, but I'd still take a careful look.
Definitely go with the synthetic fluid, especially if you plan on using the tractor in cold weather.
When you change or add engine oil, be EXTREMELY CAREFUL about putting oil in. Leave the dipstick OUT and pour the oil very SLOWLY. I play it extra safe and give it 10-15 minutes before I try to start the tractor. Pouring the oil fast can cause oil to lock up in the upper part of the engine somewhere and ruin the engine. There is a service bulletin out on it from quite a few years ago. Mice can get behind the dash and raise **** with your wiring there. They were kind enough to (barely) leave me enough wire for my fuel gauge to be able to splice a new piece on.
I have an RFM for mine and given the work involved with mid mount mowers, I don't think I'd ever get one for the TC26DA. A 60 inch or larger mid mount doesn't make it easy to get at blades and such, and while it's not easy with the RFM, at least I can do it. Don't lose any small parts. They cost an arm and a leg.
If all is well, that is a very good price for one of these. What kind of land do you have? These are a little on the tippy side, so you have to be careful.