You have a tough one there.
You can buy the 101 Detroit from Jegs IIRC so I'd just compare to that and adjust accordingly.
The axles themselves are strong for a Rover but are really only 22 spline. The casings, however, are good and strong but not outstanding given what is available in the US. If they had a disc conversion they'd go like hot cakes but with stock drums they're interesting but not hugely sought after.
Those CVs are nice but have no real value to most 101 owners as they these trucks tend not to get pushed as rock crawlers but are instead load haulers and mud pluggers where stock CVs are at least adequate. A rock crawler would probably drool over them though.
You are also selling into a very limited market if you are looking at 101 owners in the US. As 101 owner who knows my parts and shipping sources and with time to kill I'd offer you approx $2K but I am NOT the customer you want.

If you want to achieve some decent return I'd look at the Land Rover hybrid/crawling crowd. Ask over on G'n'R as I think they are more in line with your market.