I recently received a non working X68k Expert HD system. After a failed attempt at rebuilding the stock power supply, I found a small ATX replacement and shoehorned it in. For others looking to perform a replacement of their power supply, the unit I used fits great!
Its an Apevia ITX-AP250W
At the time of this posting, they are available from this seller: http://www.ebay.com/itm/110788590530
And here's some pics of it before and after installation. Note I plugged the original PSU fan into the connector inside the new PSU and removed the new PSU's tiny fan.
And if anyone wants to attempt to recap their PSU before it blows and destroys diodes etc, here's a cap chart I made for it: