I have one 10 minutes form my work, wander in, fill up 2 48ci tanks and I'm gone pretty quick haha.
I only use HPA for GBBR's and pistols so I'm not pumping out 1000's of rounds, enough to warrant a scuba to fill me up during the day.
I would suggest play a few games and see what air you're at after, if you're running low by the end or mid way then perhaps a scuba could be a good investment.