they seem to be about £3k here you're right, but there is a limited choice.
The importers were Rosetti but I think they have finally lost the import deal to Gibson Europe who are now doing it direct, this may be good news and we may see a few more Historics come over, but if you check out the stock that some like Wildwood Guitars have in the States, you'll be amazed.
If you're looking for a real Good one I'd look first in Japan. The pecking order seems to be Japan, USA, Europe. I don't want to decry anyone's guitar bought here in the UK but when you see the stuff in Japan , you just walk around with your mouth wide open.
I don't want to offend any Japanese people but they are fanatical about these Les Paul's. There is a street in Tokyo which is about half a mile long and both sides of the road are nothing but guitar shops, not just on the ground floors either, The shops are sometimes on the second or third floor and it appears that they al;l have a great choice of Historics . I am always like a kid in a sweet shop when I go there, The guitars are all usually hand picked beauties.
here's a couple of links to USA places
http://www.marksguitarloft.com/http://www.wildwoodguitars.com/electrics/gibson/enjoy