I don't think you'll find everything in one place ... for the whole build ......but as far as populating the PCB .... everything on there with the exception of the Sozo caps were sourced from Mouser . Jason supplies part #'s for Mouser on the BOM . I believe you can get everything from Mouser if you want to go Cornell Dubilier where I have the Sozo's .
I also subbed what ever resistors he had on there for these Vishay Metal Films that I stumbled onto on the Marshall forum . They have a 1W size footprint but are rated for 2W . I used them in my 2204/JEL Build along with Sozo's and I'm super happy with the results .
I had to go with two different vendors for the Sozo's ( someone is always sold out of one value you need )
Headshell , Trannies , and chassis came from Ceriatone per Jason's suggestion ( careful here ... great prices till you get to shipping )
I'm pretty sure all the other Off board hardware with the exception of Tubes came from Amp Parts Direct
and I bought some of that Teflon coated wire from I think Tube Depot .... this stuff is incredible .... you can't melt this stuff ... at least I couldn't .