Building a mechanical Clock
I would invest in:


sheet brass (Various thicknesses, for the mainspring, gears, hands, housing, etc etc; it's generally easy to work and looks good polished)
A Dremel or similar precision rotary tool/spiral saw (for finish work and other fine detail)
A scroll saw (for basic cuts; you can also use it for most of your woodwork if you have a steady hand or a guidestop)
Myriad springs, machine and wood screws, nuts, bolts, and other fasteners.


I would invest in plans for a known working design rather than trying to reinvent too many wheels here. Patience is key, like a lot of precision work hobbies, and don't be surprised when your first assembly doesn't work quite right.

As far as kits, you can buy mechanical movements pre-made, but not pre-assembled. I would seriously consider this as a first step in your foray into clockmaking; clocks' tolerances are REALLY fiddly, and must be very exacting in every part to get anywhere close to a usable clock, to say nothing of an accurate one.