I believe Mesa will have the originals in stock from time to time, just have to check every so often (just bought one myself not too long ago).
Another option is the aftermarket all in one from Switch Doctor. I have never used it but was contemplating one.
Hello,
New member here from the West Coast.
Long time lurker, new poster!
Currently have:
MARK III Red Stripe
MARK IVB
JP2C
And I plan to get a few more!