These sites can help supply you with all those parts you don't want to make yourself.
See what fits your needs
McMaster-Carr is extensive in all the products they can offer:
Fastening & Joining
Piping, Tubing & Hosing
Pressure and Temperature Control
...and Many More!
Essentra Components manufactures and distributes small, essential components
Adhesives, Sealing, & Tape
Caps, Plugs, & Masking
Fibre, Wire, & Cable Management
Knobs, Handles, & Grips