Don't recall if its inexpensive, as I bought mine so long ago... but ACS sells a MUST have flaring tool kit for doing 37deg flares.
Also... another note... tractor hydraulic fittings it turns out are 37 degree. Had a local farmer/RV builder clue me into that one. They can cut your surplus aviation braided hose and put a nifty brass 37deg fitting on it for about $2.00. The pressure on hydraulic hoses is enough that you won't even consider worrying about fuel leaks at < 10 psi. I bought some nifty AN hose at an airshow and got it cut with fittings installed for less than $10. Ok so they are brass and weigh more.... but they are CHEAP!
