It does seem Letraset has gone the way of the Dodo. (the forum spellchecker fails to recognize the name). These folks sell custom made rub transfer labelling
https://imagetransfers.com/blog/how-...from-letraset/ I've never tried them but it seems an interesting concept.
Yes, it is possible to print your own water transfer decals (also called water-slide in some discussions). There are several catches to be aware of - printing white with inkjets (Alps used to make a printer that could print white) or lasers isn't the easiest, not all inkjets will work with water resistant ink.