2007 sunlight m-865se looking to buy one for $4500

I would not worry about the manufacturer no longer being in business. I bought a 2008 Lance 845 and when I contacted Lance in 2011 to get replacement parts they could not help me. Once the warranty period is up you are on your own regardless.

It is why I would hesitate to get a slide-out model as when the manufacturer decides to upgrade the mechanism or goes to a cheaper version it may not be possible to get replacement parts for an existing camper.