I have a 1930's Gravely walk behind tractor in good condition, I want to know its estimated worth.?

The body/chassis is in good condition with mild oxidization but no actual rust. Body is solid with no brittleness. All parts working and original engine in great shape. Looks 20 years old, after 73 years. Fortunately I live in Alaska and the atmospheric humidity is very high in PH so there is very little to no acidity in our rain water and it tends to keep things from rusting and has allowed this little gem to stay in great shape for close to 80 years. I want to know an estimated range that it would go for, even at auction, in bad, decent, good and great condition so I have a general idea of what to look for in selling it.