Could you phone a few local engineering places? If they have one i'm sure asking to tap one hole for you would be cheaper than buying a tap in the first place.
3 days on perhaps he dont need or doesnt know the thread form required.
The list of threads is endless BSW, Metrics, UNF's, ACME, etc. On a 3/4 hole- 19mm bore is 1/2" BSPF a bitch to cut by hand in steels.