Source for 4-5 70mm Film Backs Mamiya RB

They used to be available for $100 at KEH. They used to be all over ebay. Then a bunch of damned hobbyists bought them all.

I am in the situation where I need at least 4 70mm short backs for wedding photography and event photography for jobs, and I can't find any. I have 100-foot backs for my RB, as well as long-roll school photography cameras, but nothing portable for shooting.

Can anyone tell me of a source for a back? I'm willing to pay decent money, i.e. more than KEH, but not $2 grand for one.

Also, if anyone can steer me to a source for 15-100 foot70mm reels for processing B&W film, I'd appreciate it.

I have one that I could sell ya. Does not include the vacuum bulb or hose.

BH Photo has a used one:

http://www.bhphotovideo.com/c/used/33827/Mamiya_214604_Film_Back_70mm_for.html

Thanks for the responses guys, and for the link Tony D.

Keith, I've never used 70mm backs before. If I have a bulb and cord from another back is it possible to pre-de-pressurize several backs with one bulb, or must the bulb and cord remain attached to retain pressure? If the former is the case, I am interested.

I think you can quickly detach the line and bulb, kinda like a blood pressure bulb. I am not 100% sure because I haven't done it, but I think you only apply vac for each shot, one at a time, when really concerned with critical flatness. I am guessing that in a fast shooting situations you wouldn't use vac at all. I never thought of using the vac- too many other things to worry about with the rb I think if I were really concerned with flatness I'd use one of my 2.25x3.25" sheet holders with the rb.

Speaking of my 70mm back, where is it?! I don't see it on my shelf. I wonder if I loaned it out....