My opinion, I would offer 300-400 and go from there. I'm down by Indy, and know what I have paid for things is Central Indiana and Central Illinois, so this is part of my price. In some places, this stuff would be worth a lot, and somewhere that Cub Stuff is more plentiful (like Cubsylvania) it would be worth a bit less. Parts are available, the colorful boxes at the top can help you out there.... Plus the 1282 runs the K321AQS Single Cylinder 12hp Kohler that 1200/1250 Quietlines do.
This is just one persons opinion of how I would approach it. Some would say to offer to "haul it off to get it out of his way", or offer "scrap" price. Someone else my say you should start at $1000..... Me, I would go with cash in hand, pull out $300, and offer it. Have a max that YOU are comfortable with.... and stick with it. If you want to stop at 600, then one of two things will happen, you will have a trailer full of new toys, or 600 bucks in your pocket. Remember, cash is king, I've gotten closer to the deal that I wanted with the offer, in my pocket, ready to pull out. Keep your "reserve" separate, or do what I do, momma keeps a hold of the "wiggle room" stash. Don't be afraid to walk away. I had a couple of deals (even on a vehicle at the dealer) that I made an offer, they declined, and I got in the truck and went home. I got a call before I even made it home, they were willing to accept my offer if it still stood. Went back and made the deal.