1998 Lance 945

Replacing the windows isn't that difficult IF you can find thermal pane replacements in the same size. And I suspect it's possible since camper manufacturers dont make all their own custom hardware, they buy it from suppliers.
I'd start searching camper parts suppliers and see if you can find them.
Buying a new camper is an easy solution... if you can swallow the price!
I do agree it's probably not worth doing though.