I like the reply of building my own set,in the sizes I really use alot from one of the machine shop sites.They are in a speciality business and have vast knowledge. There are so many different solutions and taps and lubes for different materials.You also want to have quality drill bits,as over or undersized holes will bite you.A quality tap wrench,forget the crescent.Get a chart that tells you sizes of driils,there are metric,letter,number,fraction,you have to think like a machinist.It makes a big difference if you are chasing a thread or cutting a new one.The tooling might effect the quality.Practice a bit before,if a tap or set can't perform in practice,its time to upgrade.Another sitiuation where you want confidence in your tool selection and your abilities. Don't skimp,buy once.