If you've ordered the Gristleizer PCB, you've surely received the BOM (bill of materials). In general, it has the part numbers for most components, some from Mouser and some from Jameco. They're both easy to order from, and everything comes packaged in nice little plastic envelopes, all labeled.
For all the resistors, capacitors, diodes, ICs, transistors, pots, switches, etc. I ordered what was on the BOM. Actually not 100% true... one of the caps was out of stock, but it is easy to order one with the same specs.
For the knobs I ordered Jameco 264946. They're a bit larger, and I like the look.
For the audio jacks I ordered Mouser 568-NYS229L, since I didn't want on-board jacks.
And for the enclosure I ordered Jameco 209358. It is a 7.5 x 9.8 x 3.2 inch case. Rather big, yes, but that is what I wanted, especially for mounting the knobs, switches, and audio jacks on top.
I also ordered IC sockets for all of the ICs. Though hardly required, it just provides a nice peace of mind.
With the exception of the case & knobs, I actually bought enough parts to make 2 Gristleizers. If I like this one enough, I'll grab another PCB to build into the modular synth I'm planning to start... sometime...