Recommendation for 4x5 and 8x10 drums?

Supply and demand. I do not think Jobo has any official distributors in US. This is why our friend (there was a url link here which no longer exists) is happily in business.

My Jobo 3004 Expert drum cost some $120, two thirds of which was sucked by customs office vampires. And I got half a kilo of original München dust with it. Sometimes you get lucky.