Try to find a local electronics store, not Radioshack, but something commercial grade. I have a place I go where I picked up my ATC fuse box (for internal use) that has a common bus. That is, one power wire feeds all of the terminals.
As for the weatherpaks, you'll need to order those on-line. I thought about using weatherpaks, but my car never sees inclimate weather and I could not justify their cost right now.
Hugh, your wiring embarrasses mine!