There was a discussion thread three back in this list (sorry can't figure how to link it direct

One 'as new' stored since '74 bid up to $7,200.
One custom ratio, polished bid to $6,100.
Third was pulled and sold locally.
I say 'bid up to' as one never really knows with eBay whether these are real consumated deals.
If luck is on your side, and your prepared to wait you can get one at a reasonable price. I saw a rebuilt one, zero miles about 2 months ago on eBay go for $3,000. It was poorly described just with 'ZF' in the title.. so any detailed 'searches' missed it and it got lost in amongst the other Ford and BMW ZF boxes.....keep your searches simple, even if it does mean looking through a couple pages of 'hay' to find that needle

Julian