Ace, I left a reply on the other post you had, but as far as tools, you CAN go overboard.
A pack of needles, good waxed thread, a good leather awl, a sharp utility knife, a cutting board, and leather can get you started making a plain holster.
For more finishing get a stitch groover and a overstitch wheel. It makes your stitching soooo much better.
You will want to add a beveler and an edger for smoothing the edges, but you can use a piece of deer antler for that.
If you want to decorate, the Basic 7 set is good, and comes with a cheap swivel knife and 6 commonly used stamps.
Eventually you will want to add more stamps, and Ebay is a good spot for that, especially if you visit the seller stores, not the auctions. Many have the stamps listed in the store for 3.00 or so, but when they hit auction they climb significantly.
There are many other things that I have on my bench, and many I have only used once. I would suggest getting only what you use, and as you need something, then look for it, or make it. By the time you have a few projects down, you will have more tools than you know what to do with. Good luck. DM