I cant tell you what you should get... I can only tell you how I went about getting into leather work....
I have always been attracted to working with leather, more than wood or other hobbies. I ended up with a little extra money one fall a few years ago and found myself at my local Tandy store. I bought the wholesale membership first then turned atound and bought the "ultimate leathercrafters" kit (http://www.tandyleatherfactory.com/products.asp?number=55512-01). I have used almost everything in it, and there are a few items that I have not used.... and there are a few pieces that i have since upgraded. I still to this day use the swivel knife that came with it: http://www.tandyleatherfactory.com/product...number=35050-02
But moved up to the Ceramic Blades: http://www.tandyleatherfactory.com/product...?number=8027-00
And like Beaverslayer did, I also went to a counter top place here local and asked to pick through the "scraps"... I found a nice piece and was charged $10 for it. I was expecting it to be either free or way more than $10 so i was more than happy to pay the $10. I also went to ebay and tried to find stuff... but most were in large lots that cost way too much. I did however get a good deal on a head knife.
If I had had this place to come to before I spent all the money I did on the kit, I would have come here to find out as you have. The tools I use from the kit religiously are the hole punches, the thong punches, the cutting/punching board, utility & round knives, rouge, swivel knife, some (not all) of the stamping tools, the button tools, the small anvil, and a few others that i cant think of right now.... I have added allot of other tools to my rack, some that I have found I like, some I found that I done... It is (to me) a matter of trying it out, seeing if I like it or not....