Tractor itself looks decent, although it's hard to tell much from a photo. Give it a good tire-kicking and make sure everything is in good shape mechanically. The mower and blower sure look kind of rough, just going by the photos. They weren't cheap to buy... you'd think the owner could at least clean them up if he wants to sell them. I'd want to see both attachments operate, look for worn spindles, shafts, gearbox, etc. If that degree of attention carried over to the tractor itself... But assuming the tractor is OK, $4k wouldn't be a bad price for the tractor, and those attachments, if in good condition, would make $5k an OK price.
How does one only put 660 hours on a tractor over 30 years? 22 hours a year? Maybe the mower and blower were not used to any extent and just sat somewhere gathering dirt and rust. Has the tractor been serviced?
All this is just one guy's opinion. Good luck!