I wouldn't use compressed air from a gas station no. As mentioned, there could be compressor oil in it or equally as bad, condensation. Mechanical air pumps/compressors are notorious for this. Even working in an auto shop where it was frequently maintained, the amount of condensation that ended up in the air tools was ridiculous. After using for awhile, your hand would be soaked as would the back of the tool and connecting to an air source meant a spray of water. Not something I'd want in my pc (I didn't even want it in my air tools and they weren't electronic). I've had this happen before airing up tires from service stations where compressors for public use are often neglected and not drained often (if at all).
Something like that datavac would be a much better option. That or compressed air in cans, though I haven't seen a can of compressed dusting air for under $5 in awhile. Still a far better choice than service station air. $5 beats saving $4.50 and ruining a $100-300 cpu or something else.