For B&W from Veronica Cass start with this kit:
For Azo/amidol/selenium, I find I can use the Mauve dye almost straight, maybe with a dab of Midnight blended in. One thing I like about these is that if you make a mistake, you can re-wash the print and they come out pretty cleanly.
If you get Spotone dyes, just get the three-dye kit. I've never needed more than that.
Are there really ten brands of retouching dyes? Spotone and VC seem to be hanging on by a thread. I've seen Kodak dyes, but I think they have stopped manufacturing them, and maybe Marshall's would be another possibility, but I've only used their photo oils.