I have had two pumps but have never actually used either. I bought a Hill MkV many moons ago and it has not even been assembled, let alone used.

Before I got to use it I saw a bottle at a decent price, so bought and used that. A few years later, I got a compressor that will fill guns and bottles.
The other pump was a few years ago when, I think it was on AGF1, someone spotted Amazon were flogging Chinese ones for a fiver, so I bought one. Again, sat in the box for a few years then I thought I'd assemble it and see if it actually worked. No assembly or usage instructions, I'd either lost them of never had any, and aI couldn't get it to work.
No idea if it was me being dense, I'd lost part of it (the box was open and the contents had fallen out a few times

) or what.
Whatever, ended up at the tip. As said, it's possible to get a compressor for the same price as a new Hill pump, I'd expect. Same with second hand dive bottles, which is what I picked up.