Myrrh ink is used in several of the papyri, both Greek and Demotic, and Dr. Flowers even includes a recipe in the appendix of Hermetic Magic, but do any modern practitioners actually use it?
Searching online for further information on myrrh ink yields nothing but PGM results. Researching magic inks, not something my practice has hitherto made use of, it seems dragon's blood ink (not necessarily an appropriate substitution for the PGM, even in workings where dragon's blood may be appropriate, given its colour) is the magical ink of the post-modern magic worker's choice (either that or dubious "magic ink", with no information about what makes it magic or so expensive, of whatever colour you desire).
Personally, I'm inclined to buy fountain pen ink and consecrate it after adding appropriate essential oils. What do you do? Do you bother with special ink at all?