The things I use most-
Good leather
Belt and drum sander
Drill press
Stitch groover
Overstitch wheel kit
#2 edge beveler
00 John James harness needles
1mm Tiger thread
Bone folder
Basket weave and camouflage stamps
Dyes (Fiebings)
Glue (Weldwood contact cement)
Gum tragacanth (can use wax or saddle soap)
Hardware (d rings, 1" round rings, Chicago screws, line 24 snaps with setter, and I just got a bunch of Sam Browne studs)
Utility knife
Cutting mat
Then I have a ton of other odds and ends that I don't use as much, but come in handy.
I'm slowly replacing pretty much everything with pro quality tools.
I'm always tempted to get a stitching horse or pony (especially if the customer wants two rows of stitching) but so far my knees are working fine.
I've seen some very fine work done with very minimal tools, but the above is a good starter kit. You'll likely end up with a bunch of different threads and needles and tools if you stay with it.
Good luck
