I used "Rapid Air" flexible line, bought 100 ft for $48 @ amazon,
bought fittings at "http://www.stcvalve.com/Push_In_Fitting.htm"
have maybe $140 invested, (30x50 shop)
I've used PVC for years ( 25 PLUS yrs) with NO issues ever!
but was concerned as I have a couple valuable collector cars in the garage.
didn't want any surprises,
I run 150 to 175 PSI all the time, so ........
you be the judge,