Information on Nikon MF-10 data back..? Recently purchased one on a standard F2.

So I recently purchased a beautiful standard Nikon F2, with an MF-10 data back attached to it. I had only read about the F2 data a handful of times, and it turns out that finding any more information on the MF-10 is proving to be much more difficult than I had imagined.

While I would appreciate just about any information about the MF-10, I do have some specific questions that I was hoping someone could answer for me.

Was the MF-10 sold separately as an F2 accessory, or is there a lonely F2 data missing its back now?
How many MF-10 backs are in existence? I know that the F2 data numbers have been estimated to be ~5000 or so, but the MF-10 was not the only option.
Lastly, the question of value. How much does an MF-10 with very little perceivable wear go for these days? I'll probably just end up keeping it for my collection, but I still like to know the value of all of my gear. I could not find anything at all in regards to value, aside from the actual F2 DATA.

Thanks in advance!

Have you seen this site? http://www.mir.com.my/rb/photography/hardwares/classics/nikonf2/filmbacks/index1.htm#MF-10

They state that the MF-10 was made to order with specifically modified bodies.

Looks like that back would be pretty rare.