www.rockstarsguitars.com
That's where quite a few of them were auctioned.
They did actually make a limited edition RS doubleneck Kramer but, with only 12 ever coming off the production line, you'd be hard pressed to find one and even harder pressed to afford one.
Ed Roman guitars has two I believe (or did have) but he was charging such an astronomical amount for them, it would probably have been cheaper to track down and buy the one Richie actually used on tour!
