It would bring more than $750 around here. Assuming there's nothing wrong with it and the hydraulic cylinder works, I'd give $1,000 - $1,200 in a heartbeat if I needed one. Mine is very similar to yours, although mine had much more "character" than that one does, and I paid more for it than you've offered. Mine has the swinging tailgate, and it doesn't look like that one does. After using mine for a while, that would not affect my decision to buy one, as I usually keep mine locked down.
Buy it, flush the old oil out of the cylinder, go to Tractor Supply and replace the hoses if needed, and you'll be in box blade heaven. Let me warn you, though, that mine will stop my DK50SE HST dead in its tracks if I load it up too much. But it's all the box blade you could ever want unless you upgrade to a much larger tractor.