This is probabaly not helping at all, but......
ishibashi.co.jp only accept bank transfers anyway, so you don't need a credit card.
The drawback is that they don't have the RG421, but they have the RG621.
Sale price 52,000 JPY (£272), bank wire charges 3,000JPY (£16), delivery to the UK 16,500JPY (£87).
Total cost before VAT and Import Duty = £375
Then you'll have to pay around 22.5% on top of that to HM Customs and Excise.
So for around £460 you can get RG621 imported from Japan.
I'm thinking of doing it with the RGR580JBB - It'll cost around £500 for a solid mahogany RG with reverse headstock.
It'll be the best Xmas present I have ever given myself.