Cost - around a tenner, I think.
Source - Monarch Airlines flight to Barcelona.
Having struggled with a 'pour-to-fill' perfume dispenser in the past, I couldn't resist this one.
It claims to be easy to fill, leak- and squash-proof, as well as lightweight.
I was surprised to find no instructions, but a picture on the box said it all. Just pull the top off your spray perfume, sit the dispenser on the top of it and pump away. It doesn't take long to fill. You can see the perfume going in, and you'll know how much is left 'cos there's a window in the side.
I haven't yet tested it in an aircraft to see whether it leaks, so I can't comment on that claim. I like the product overall, but the spray is a bit erratic and I had to press hard on the button to get it to deliver - and that squirt was more generous than I'd like.