If it's really finished other than the flooring (ie, insulated drywall walls, nice windows, window coverings, finished ceiling of some sort) then I would think flooring it would be a no brainer. Glue down LVP is great because it's waterproof, but it can telegraph any floor imperfections so the floor needs to be flat. I used groutable vinyl tile (from a big box home retailer) and, as a first time installer of any sort of tile, it took a while but was not difficult at all. It was somewhere around a buck a square foot plus I had to buy grout, spacers, and the tools needed, along with a good set of knee pads. They cut with a utility knife. You'd be well under a thousand dollars by the time you're done, and you'd have a new skill.