Browsing the internet I found http://www.gvp-m.com/
It looks to me like they are still or again producing various accelerators for the Amiga. At $495 for the Amiga 4000 / 68060 / 64MB board this is not even a bad price, given that I've seen Cyberstorm MK2's go for €300+ on Ebay...
Is it a hoax, extremely outdated site? Or should everybody looking for an upgrade consider buying it from GVP?
I ordered and received a A4000DT-060 Accelerator with 128Mb through Software Hut 3 months ago and it works fine. It is a Revision 2 board.