nah, he's talking about custom dyes, not stamps.
one of our customers is the guy from Chain Reaction DG who is an awesome dyer and (in my experience) has some of the best slow-fading dyes. like any badass he keeps his secrets, but i know his stuff is an industrial dye made for plastic and it comes from asia through a catalog.
now, here's the thing you don't hear about RIT. it's not just 1 dye, it's an all-purpose craft dye, a mix of dyes made for different materials. there are various fabric dyes in there along with legit plastic dye... the fabric dye does absolutely nothing for your discs, really only the plastic-specific dye included in the RIT mix is dyeing your plastic.
the "pro" dye is more industrial and specific than all-purpose craft dye like RIT. pro dye often has the solvent (normally acetone in disc dyeing) included in the mixture... so you're getting an acetone/dye liquid mix. the solvent type/amount can be very specific to the type of plastic it's for.
the proper amount of acetone will have positive effects on your dye. too much acetone and the dye continues to bleed and leach through the plastic. a lot of home dyes either used too much heat or solvent/acetone.
getting the right industrial dye would take A LOT of trial and error. basically you don't know much about the plastic on a compositional level, so it's hard to find the dye that would best chemically bond with that plastic. not that you couldn't find suitable dye.
i want the dayglo dye colors... that's just sick.