Yes the E63 M6 is much more widely available than the E92 Alpine White M3.
There are a number of colour's available. The one in my post above is Interlagos Blue, which was a dealer edition colour. There's none available at BMW or eBay UK, but there is one
available on eBay Germany for £55 inc shipping.
The non dealer edition colours that are still available are (and you can buy from the UK)
Sepang Bronze for £50 inc postage.
Silverstone silver is also available for £57.49 inc postage.
Just to let you know that the dealer edition Interlagos Blue is a little inaccurate as the front lights were not made correctly. Kyosho made them all silver, so you cannot see the angel eyes. This error was fixed on the non dealer edition models, as my grey one below shows:
Raj