Kevin Federline by Joe Kohen/ Kevin Federline by Joe Kohen/

Britney Spears' ex is hot to hook up with Elle Woods, but thus far a matter of greenbacks is keeping the actor-rapper off the Great White Way. Kevin Federline had been in talks to join Broadway's Legally Blonde in any of three roles (including the delivery man who dazzles Elle's manicurist pal), but the negotiations "fell apart" over a "money issue," a source tells Us.

K-Fed is reportedly "really upset, because he wanted it to happen" - and it still might. "He wants to do it," says the source, "and maybe it can be saved. But for now it's not happening."