Dye-your-own would be fairly easy and cheap to implicate using youtube videos as instructionals, and assuming you will already have a computer and a printer. (bonus if you get an actual vinyl cutter/plotter http://www.bestblanks.com/graphtec.html
). Beyond the computer and printer to print stencils, all you need is:
-vinyl (this can be had for free from 3M by requesting a trial, they gladly give out samples to disc dyers),
-transfer tape (lint rollers work great for this)
-RIT fabric dye. Theres about 50 colors but a basic red/blue/black/green/yellow works, and it is re-usable
-acetone for removing the stamp
) and x-acto blades if you dont have a plotter (and lots of them, they lose their edge pretty quick)
-pie tins to do the actual dying in
-last but not least, some source of heat to heat the dye. it applies much quicker/better if its heated to about 150 degrees. Microwave or portable burner works.
also, a dedicated area for it all to be done in, because the acetone and RIT dye smell nasty, and its nearly impossible to not splash the dye around where you're working.
If you have any other questions about dying feel free to shoot me a message. Theres also a few people around that do this as a side job in their free time, perhaps you could sort of "rent out" a space for them to put on workshops. They benefits from the disc/dye sales, you benefit from beer and disc sales without having to invest in all the equipment.
EDIT: I just recalled I've actually seen this done before where a disc shop had rented out an old restaurant and used the kitchen space as the dyers workshop. Pretty cool actually, and if you took it up yourself it would be a great way to get some profit. A well done custom dyed disc can sell for $40.