I work for a small UK charter company with a brand new fleet of B737-800s, and IFE equipped. We charge £3 ($4.20) for headsets, which can be taken away for use on further flights. We have no problem with people using their own headphones, even if obviously bought from another airline.

I think TWA as a big company - or any other for that matter is big enough to absorb the cost of a few people using their own equipment. I think it only serves as poor PR and puts the FAs in a potentially confrontational situation with the customer.