Are there are many Blazers in Vermont (east coast)?
15K is the absolute lowest you should go.
You might want to get that AC charged if you are going to ebay it. When someone reads AC not charged, they chalk it up as AC doesn't work. Especially since you will be probably be selling this to someone that wants a "move-in" condition rig, because the rest of the ride is ready to go.
The only other thing that might hurt you is that you are selling it in the fall.