If you were going on a long-haul flight and you had two airline options, and one of them had PTV´s but not the other. Let´s say that the airline with PTV´s cost more. I would pay €50-75 for that.
How much would you pay??
Depends on the service and airline as well. It would be nice to have a PTV but if the airline or service was not as good as another, I would leave it. Service and comfort come first. Food second and as long as I get a window seat, I'll be entertained for hours.
Since I can't sleep on airplanes I have to have something to occupy my time with. So PTVs are very important to me. I think I would pay 50 euros to ensure PTVs. I hate to endure another flight like I did with Qantas LHR - BKK with a broken entertainment system. 11 bloody hours with nothing to do. Not fun.
I would not pay more for a PTV - however, I would be willing to pay a little extra for better seat pitch, healthier seat ergonomics and improved general realiability (i.e. punctuality, cleanliness, safety) of the airline's operation. Maybe a sum in the 50-75 Euro price range, depending on the travel distance.
Homer: Facts are meaningless. You could use facts to prove anything that's even remotely true!
PTV's are a nice thing to have, but I would place them fairly far down my priority list for things I would be willing to pay extra for. Higher on the list would be seat pitch, food, service, quality of interior.
I regularly have 12 hr + flights and for people like myself, who never, absolutely never sleep, the PTV's are really helpfull. Don't know how much I would pay extra, but 50-75€ is not that much considering the benefits.