3 years ago, when I was looking for a Class B, I could find lots of 1995's & 1996's. 1999 to 2001 were hard to find.
I think the unit you're looking at is a Class C. From CRVA:
Class C Motorhome: sometimes referred to as a mini-motorhome, this unit is built on an automotive manufactured chassis with an attached van cab section.
The RV I have now is classified a B+ by the manufacturer. B+ isn't an "official" category. The floorplan you're looking at might be similar to mine:
Mine doesn't have overcab sleeping. I saw one 1999 21' Gulfstream Yellowstone on the web - I like the layout. It's hard to find a 21' Class C - all of the units are getting bigger.
Do you know how many miles are on the odometer? 1999 is not old but I'd probably budget for tires (if they're original). Brakes & shocks should be checked.
The unit I saw on the web looked like it had an oven, dry bathroom, large fridge - all very nice to have.