Okay, just some rough ballpark numbers, that may or may not be reasonable depending on your location, and with which others may totally disagree...
Anything under $2000 is probably gonna be a nice looking parts vehicle.
Something in the $3000 to $6000 range should be a solid, clean, reliable (for a Rover), capable of being driven. However, not necessarily the sharpest paint job, or strictly original, or particularly unique.
$8000 to $10,000, it'd better start to be dead-on sharp.... nice paint, no problems, no rust. Not basic, but kitted out nicely (winch, overdrive, rack if you like, etc.).
If you have something a bit more unusual, like a Dormobile, or a Carawagon, it can go for more. Especially if complete and functional, and hasn't had parts stripped out.
I've adjusted these numbers down.... the Series Rovers that I saw going for $18k to $22k five years ago, just aren't commanding those prices now, unless you just happen to have a buyer to whom cost isn't a consideration and don't mind paying anything that someone asks w/o having an idea of where the market should be.
IMHO, FWIW, YMMV.....