After plenty of reading I decided to skip P3Steel kits and instead gather parts myself. It was hard to tell which version kits are based on and the quality of threaded bars and smooth rods was a big question mark. Currently the frame pieces are being cut by a laser cutting shop, server PSU is on the way, bags of M3 nuts and screws also ordered. I set up a simple blog for this build:
p3steel.blogspot.fi