In my area (S.E. Michigan) 444's like that are listed for around $800 and they seem to be for sale for a while. Heres a 446 with a 48" snowblower, mower deck, pull behind sweeper and an agrifab 10 pull behind dump trailer. It looks a little rougher than yours but does have the bigger engine and a few implements.
I would say 1000-1200 in nice shape like that, a little more if you had the deck. I did see that one on the list for $850, but its been sitting for years and it says it had problems before that. Thats a real nice looking tractor, I wouldn't give it away.