But don't forget that that guy was converting Swedish Krone to US Dollars (and now the Krone has been replaced with the Single-Currency Euro), so prices may not have been accurate.
And if you have spare fans/memory/bitz lying around- then it could be cheaper than expected, That Eden Mobo is the 2nd lowest board- but new versions have been released with better multimedia managment, so the prices of the older boards (like the C3 800) may have fallen a bit in price.
But unless you just want to mod the PSX box (only easily viable mods would be to add windows & some sort of heat managment) then Mini-ITX boards are probably the best way to go.
Hey Wolfe, you got pics of that mod? That'd look kinda cool.