I've started doing kitless too and it is quite a learning curve. I don't think anyone is doing any group orders right now (I assume you mean for stuff like triple start taps and dies?). I think all of the specialty taps and dies that I've seen are made by Tapco by special order. Lots of places do sell standard size taps, dies and odd sized drill bits; I've gotten most of mine through Victor. I gotten my triple start taps and dies from Turner's Warehouse. Specialty taps for Bock and Jowo nibs/feed/housing/sections can be gotten through Turner's Warehouse and Beaufort Ink (Bock only). I bought tap guide and die holders from LittleMachineShop.
You are probably aware of this already, but if not, there are a number of useful tutorials here in the resources section that deal with topics like turning closed ends, turning fountain pen sections, and one on kitless pens that focuses pretty much just on turning and tapping a barrel and cap. Aside from these general tutorials, I'm not aware of any step by step guides. I read the advanced pen making forum start to finish, decided what kind of pens I wanted to make, spent some quality time with Fusion360 measuring and designing, then figured out what tools I needed. I've gotten a lot of help by asking questions here, but you'll need to define what you want to accomplish pretty specifically before anyone can give you much advice.
