If this is a 260 bumper, it may be easier to just replace it. They're extremely affordable online and at train shows (less than $10 for a nice, clean one).
You must have found a some that I missed. Plus the average shipping $6.50+
Recently sold listings on the Bay:
2 for $9.50
4 for $16.50
2 for $9.95
12 for $62
Most of these had original boxes and occasionally paperwork.
Shipping ran between $3.00 and $8.00 on these listings ($13 for the 12 bumpers)
At the Greenburg show in Edison this spring I bought 6 of them for $30, 4 of which were boxed and had paperwork.
I agree with all that you say Andrew B. These days, if a 260 is >= $10 at a show, I just keep moving because there's no point in even bargaining. 3 for $10-15 is the new set point.