It does look nice. I'm thinking those white leather couches probably weren't cheap. It's tastefully done. It does have some nice furnishings and a pleasing appearance if you just wanted a large living room and (I'm guessing) a small bathroom.
You should understand how difficult as it is to try to determine a value based on interior photos, but by first impressions I'd guess that bus needs a full build, like any other bus. If it runs well it should be a good platform to build on. I'd also be concerned about the age of the tires as well as the mechanical condition of the engine.
It appears the bus has its original ceiling panels, indicating there is only factory insulation in the walls and ceilings. Given it's age combined with the likely need to be completely stripped out and rebuilt, I would value it on the low end for this type and age of bus.
In comparison there was recently an '99 MCI in auction at about $4500 as a coach with all the seats remaining. It's not uncommon for a factory original coach to sell between $10k and $20k, or more. There are some good deals around.