$200+ worth of rear tires there.Looks like 26x12-12 ITP Mud Light XL
Accually $575 is reasonable if you add up some numbers on the stuff.Plow $100-$150? large frame Tiller $200-$250 around here and the tires at $200-$250 shipped on Ebay.
If you are buying it to use I can see why that might seem high knowing that the tractor needs work.If the engine runs good I think it would be a good deal.
Mention that you might have to replace the whole transaxle and driveshaft assembly.I bet you'll get a better price on it.
I'm with EricFromPa on this . bargin a bit, who knows they might come down on price, but overall, I'd do it in a heartbeat if I were close by. Heck, I could use the tiller driveshaft!!!