Here is an Ebay auction for one used C5OE bare head by Ebay member " sjperf" with a starting bid of $29.99:
This is a 1965, casting number, pre-owned cylinder head(1 only) for a Mustang, Fairlane Hi-Po 289 cu.in. engine. Casting Number: C50E, Date Code: 4M17. The head is bare without, intake or exhaust valves, springs, retainers, valve keys, valve seals, rocker studs or other related valve train items. The head has been thermal cleaned, blasted and mag tested(no indications of any cracks). There is minor damage to one combustion chamber(see images).
Applicatioin: 1963-1967 Ford 289 Hi-Po V-8 engine in a Mustang or Fairlane.