Air compressor's

[MAXFACTOR]

Dear Fellow Diver,  cheap air.... lol..
I would not recommend your comtemplation of "helping your fellow diver" with "free or low cost air.

LET THE DIVE SHOPS PROVIDE THIS SERVICE TO YOU.  I agree entirely with the previous response, except for getting the best equiptment.  What I mean is that you should not purchase any compressor, unless you are prepared to buy the insurance. 

Chances are, its going to very expensive and the cost should be an automatic NO GO  for you.  Many dive shops cannot afford the cost of insurance, and they are filling these things daily for pennies. 600 to 800 of them per tank. 

Then your buddies may also want Nitrox mixes,  are you going to do that too?

WHAT I WOULD LIKE TO SEE, is that the Local Dive Shops, only charge for the gas used.  In otherwords, If you still have 1000 pounds in a 3000 PSI tank, and you want to "top it off" before your next dive, you should only have to pay for 2/3 of a normal air fill.  That would be very fair.   

Many dive shops around the country are currently doing this at present and many more have considered it. 

BUT.... my best recommendation is to leave it to the pro's at the local dive shops.  Besides, when you go in for air, you meet the wonderful staff etc.  and get to spend more money on more things.

SOME LOCAL DIVE SHOPS are not only filtering it right, many are drying the air too.  Even less chance for contamination. etc.

MAXFACTOR