There isn't really a shortcut to compressed air
Bod has pointed out the vital issues of filters, we ideally require 'breathing quality' air, not because we would breath from it as per scuba divers, but still due to concerns with contamination of the air in the cylinder. The best case scenario is that it affects the regulator and we blow a burst disk early, the worst case scenario is a contamination flash fill explosion
Another attempted shortcut to high pressure air was the 'shoebox compressor' a few years ago. This worked as a secondary booster, you would need a workshop compressor feeding into it about 100psi or higher, which it would then boost to 4500psi ...... but take hours or days, and overheat whilst doing it, and again its unfiltered
These are a solution to a specific problem for people who are in true remote locations and cannot get access to compressed air easily
If you're after some exercise then a pcp stirrup pump can be used .... they are relatively cheap, but you would also need to make sure it has a filter and the right fittings
Ask yourself why you need access to your own compressed air, and what options you have around
fill at the sites you play, and if necessary invest in a couple of spare 3000psi aluminium cylinders and fill them all when on site
If you are away from sites and have good safe suitable land then the next best thing is a scuba cylinder and a fill rig
Buy a fill at a dive shop etc and then fill your cylinders from that
