Framed Frazier Ali "superfight" poster

I picked up this framed poster from the Frazier vs Ali "superfight" of Jan 28 1974 at a collectors fair in London, and paid what seems like the bargain price of £30.

I'd be really interested to hear if any boxing enthusiasts know the current value of this piece, so if you've seen one for sale please leave me a comment and let me know.