I have a huge RPG collection ... a whole room. Though I do not have any of the special editions of RM, I own all books of HARP, MERP1, MERP2, RM2, RMC, RMX, RMFRP, RMSS, BOTG, SM, SMP, SW and CS ... and the small books (nightmares of mine f.i.) (and novels) ... and six (?) of the solo MERP books ... most of them in english AND in german (if translated), some of them twice or more in case of main rule books.
But I still miss Court of Ardor and Umbar, Haven of Corsairs to complete my collection. :-(
Plus: I do have an arms law of RM1, but nothing else for this system.