Well, a google search for the FSP120-50GNF will show that you can buy one for just under £50 delivered. It is identical in size to the stock PSU, but it is possible to use just one of the screw holes for the stock PSU (which is enough). When I passed the 8K01 on to a friend, I kept the FSP120-50GNF, and it is still gathering dust in a drawer. Still, imho, the 8K01 is a dead end with a LGA775 motherboard, and it would be better to spend a bit more than the price of new PSU and get a Sugo SG05 which is a bit bigger but much better in terms of noise and airflow (the SG05 is not silent, just much quieter than the 8K01) .
The hard disk in my 8K01 with a Zotac 9300 ITX, a E5200 and the FSP120-50GNF was getting uncomfortably warm and I had to install a 60mm exhaust fan. It was a quiet 16dbA SilenX IXP-34-16 60mm, and it was still managing to create considerable turbulence noise through the rather inadequate ventilation holes on the side of the 8K01. The CPU cooler, the otherwise quiet Nitrogon NT07-775, was also making too much noise in the 8K01. I made a couple of minor modifications aimed at improving the airflow, the effect was negligible and, at the and, I decided to give up and move on.