Hi I've been down this route also, got a hill's pump and only good if desperate, too long to pump and slow. But couldn't afford the top end. The wife bought me a Chinese model on eb*y 193545993913 the reviews seem very good and I think theres reviews on YouTube.

Anyway not tried it yet as I had a foot op that's prevent be looking at it properly, but I've 3 dive cylinders to fill and I'm not doing them by hand

If anyone has any experience and tweaks on the Chinese models it'll be good to have some advice prior to starting the process other than read the manual.

Anyway hope it helps.

Atb