http://www.retro-accessories.co.uk/ourshop/cat_150586-Modified-consoles.html - just added new stock.
The Core Grafx II is not on there but it's the same price as the Core Grafx I. I will post overseas, cost varies from £10-£18 to do so.
These are the best prices you will find on or off eBay given the top condition of the consoles.