Me I recon at least £20K.... Sounds a bargain at 20K too..... Its as good as an ex demo that's 6 month old...
Roadsters are just so good, for a tin top of course I have the M135i
A lot come to grief on that road, (gave a paramedic crew from a helecopter a lift to the top to see to a motorcycle accident) did it in in my Landrover Disco using low range; piece of piss! Z4 would be OK as long as one did not need to cook the clutch going up and was able to keep momentum...
I like Hardknott pass, but can get busy best go early morning; its very steep so be careful with the clutch.
To stay that depends on how touristy you like it? I rent a cottage by Lake Windermere and walk into Windermere town which has plenty of places to eat etc. Quieter places which are good...