How about http://www.seraphim-guard.com/ where you can purchase PDFs from the "plain wrap" supplements for RuneQuest line? Supplements like five classic fantasy monsters and the backstab gang: five ready-to-use NPCs, with several more on the way.
I have been wondering about this myself. My site is still 100% RQ III related and as yet I have not scraped the cash together to obtain the new RQ books.
However as it is mostly setting related, I am sure conversion to MRQ should not be too difficult. From the top of my head one would have to review any PC/NPC stats and references to magic, although I tend to go for low magic so even that should be pretty simple.