A well built good running tractor with more power than traction. NAPA has filters as reasonable as any other make ($6 for oil less than $20 for air). Actually my experience is that parts can be a challenge but that could be said for other makes as well. My preference is gas powered due to my mechanical skills and this motor couldn't be any easier to work on. Since it is probably 30 years old or more the usual radiator, water pump, starter, alternator, brakes, rust. The hydraulic pump has caused many people fits but most of it is due to overstrain on the system. It may be already modified or, if needed, you can find more than one solution here.
I you buy a Bison stay tuned to this forum for help.