Shopping for something that can be livable in the winter

Ok. Thanks for your honest input guys. This is just not my area of expertise.
So a 2001 30’ Keystone Zeppelin isn’t a good winter choice. What is it worth though considering everything is in working order. Current owner started a remodel. Needs just a little trim and finish work, but mostly it’s good to go. Unfurnished (no bed or furniture). He wants $3500. Looked like a good deal to me, but I really don’t know how to say what it’s worth.