What would it take for Floyd Mayweather JR. to fight Sergio Martinez?

[thebowtod]

a arm and a leg

[Everywhere]

If Pacquiao chickens out from facing Mayweather again with new excuses...I think Sergio might be next.

[2501]

Arum and Pacquiao have admitted that Martinez would be to big and to tough of a challenge for Pacquiao, thus, admitting that they are ducking him. But what is Floyd's reasoning for avoiding such a handsome challenge?

What would it take for this fight to happen? If it does happen, should it be at 154 since Floyd beat DLH at 154 taking his belt?