I paid less than $20 for a new grommet full price at the Ford parts counter.
Since you have done a fuel pump replacement, you have seen how everything is put together. I don't see how it's possible to replace the grommet without dropping the tank.
To anyone else reading this thread. The service manual calls for the old fuel tank grommet to be completely cut away before attempting to remove the filler neck from the tank. This is done for a number of reasons. Over time, the grommet will bond to the filler neck. This make removal difficult and the likelyhood of the old grommet re-sealing is nil (as in this case). The other reason is to prevent damage to the filler neck check valve. If the filler neck is pulled out while the grommet is in place, this will damage the anti-rollover/anti-siphon check valve. This check valve can not be serviced without replacing the entire filler neck assembly.
If dropping the fuel tank, recommend following the service procedures. Cut the old grommet away. Re-install the tank using a new grommet.