Originally Posted by
kingalien
I don't know how many extenders there are on a flight although the FAs use them during the manual safety demonstrations. I saw one person had his own extender, obviously kept it from a previous flight and brought it out when he sat down and then took it with him when deplaning.
There are a lot of them bought and sold on eBay:
Seatbelt extenders
Which is where I bought mine - I simply did not want to be in a situation where I needed one and they were out of them. It folds up small enough to carry in my carry on bag, tucked away for when I need it.