that isn't pre soldered?

Careful what you ask for, when you're talking PCBs, pre-soldered usually include diodes, resistors, and the controller already soldered on, but not switches. Fairly easy but still fun to put together.

Otherwise it can be time consuming using through hole components (Phantom TKL), to near impossible without very expensive equipment, if it's SMD components like a Winkeyless PCB. That's a whole other ball game. Don't buy a DIY kit, get the SMT soldering, or you will hate yourself.

The other big name in TKL (yes, there really are that few decent ones) is GON, he makes decent stuff, but there have been issues with him shipping products from his own website in any sort of timely fashion. You can get his PCBs in kits through 1UpKeyboards, but they only ship from the US.