The most expensive air lines might go for about $100. What is the cheapest road call? It is probably a 
lot more than the cost of the best air lines. I have learned this lesson the hard way. I usually replace my air lines within 2 years, and keep a spare. The airlines that I had on my Cascadia were good. Even the best lines don't last forever. Mine did not.
My new truck will arrive in a couple of months and my air lines still looked pretty good. There were no visible signs of wear of cracking. That is until one of my lines just snapped on a hard right turn out of a customer's driveway. We had one of the spotters put the trailer back into the yard. It wasn't worth a road service call. I called a local shop and was told that it would take at least 90 minutes to get a truck out to me. It was about 25 miles back to a trusted shop. At 06:00 traffic would already be building, but I made the decision to bobtail back to the shop.
The decision was not that hard. The cost of bob tailing that 50 miles 
would probably be less than the cost of a road call. I briefly thought about switching the service line and going to the shop that way. That could turn into a REALLY bad idea. The time element would be about equal. Road service mechanics do what is necessary to get you rolling. The shop could offer me a choice of levels.
At the shop, I made the decision to replace both lines. If one went the other may not be far behind. Plus, that way I could have a spare. A spare is nice to have, but better to not need. I also put new, high quality glad hands on the lines. At this point you may as well replace everything.
This episode cost me about 2.5 hours. You can't make that up. Don't try. That is where a mistake could get compounded. Everyone, including me, makes mistakes. Don't let small mistakes, become bigger. Relax, evaluate, and move on from there.