4900 is a bit high. However, the 1882 is a super garden tractor, so built quite a bit more rugged than the garden tractor. The loader and 3-pt will add considerably to the value.
I've owned several SGT's, and they're very good machines. My last one was a 1996 1782 that had the bucket, deck, front blade with power angle, rear 3-pt and PTO, with several attachments that I sold for $6500. It had about 300 actual hours, and was in perfect shape. These tractors new cost 7-9K, very expensive at the time. They are essentially a step between a garden tractor and a sub-compact.
Is it a kwik-way loader? That is what I had, and it was made for the Cub SGT's, a very nice loader you could pick nearly 500 lbs with. New they are around $3500. It was a task to remove it and install the mower deck, I ended up welding some custom brackets to streamline the task.
Does it have the rear PTO? Or the front hydraulic ports? The front blade is awesome with the power angle, as well as the 551 blower. Any of these extras will add additional value.
I would place a value between 3500 and 4000 for the machine if the hours are close. You haven't mentioned if you've tried talking down the price? I doubt he will get that price for it. Got any pics of it? Keep us informed!
It is a kwik-way loader and it doesn't have a rear PTO. As far as talking down the price, I haven't as of yet but he did offer it as is for $4500. I only discovered it at the Kubota dealer yesterday and seeing as it was raining outside I couldn't take any pictures. I will definitely keep you guys informed!