I have these late 70s cuffs for sale with the original magnetic key. They are in very good condition and function as they should.
I am selling them for $275 USD plus shipping from the UK - though I am in New Jersey in mid-July and can ship from there which will be quicker and cheaper if buying from the US.
I actually used them whilst serving at Scotland Yard - when I joined they didn't issue handcuffs so you had to purchase your own - hence selling them now I have retired (my later issued cuffs were returned).
Please feel free to contact me at: email@example.com
I don't seem able to get photobucket to put the pictures up but I am happy to e-mail to any prosective buyer