I put one on my A10 race bike, didnt cost quite that much but still approx $1500 nzd once shipped.
Its new, easy to fit and should be reliable. But I didnt have a half decent mag to rebuild so that wasnt going to be a cheap option either.
The downside is that the long magneto nut, will not fit as the body is slightly bigger than a k2f, so have to use a normal nut, which is a bit of a pain to do up.
I put a brand new joe hunt magneto on my old norton (before the A10) and had nothing but problems with it. Ended up selling it and fitting a coil and points ign.
Tim
saw this in classic bike -just in case you have an extra 670 quid (!) laying about
http://www.bt-h.biz/