Uhm...
Maybe somebody can make a PCB design for the coldfire wich can fit the Amiga CPU expansion slot... or in the CPU socket.
I suppose it depends on how similar 68K and coldfire wirings are.
You get the proccessor free, you have to pay for the PCB being done and assembled with the resistors, capacitors, connectors, etc.
And if you give them the remaining parts, CPU, clock, (RAM chips?) they will finish the assembly for you. No soldering needed at home!
There are some companies (like PCB Train) that do this kind of thing and have good prices.
So it mostly depends on somebody being able to design the PCB. If this task is done, we even can make a large quantity invoice to the PCB makers for cheaper prices.