I always ordered just the ones I commonly used, had a couple cheaper drill indexes for the ones that saw rare or occasional use. If ordering from Brownells I had better luck with the USA made taps over the house brand stuff. Ultimately I ended up getting a better deal on better tools through MSC.
I always carried a tube from a 3/8” endmill in my apron. Inside was a #31 stubby drill, a #28 stubby drill, a matched set to go with the aforementioned but with their points ground off to make flat bottomed holes for getting the maximum number of threads when installing sights on barrels, 6-48 and 8-40 bottom taps with %90 of the taper ground off the ends, a #0 center drill, and a 4 flute 1/8” center cutting endmill. This tiny kit takes care of %95 percent of drilling and tapping operations pertaining to sight and scope base installation. If you’re using a milling machine like I was the endmill can be used carefully to plunge cut out the center of a broken tap without ruining the hole.
I’m partial to Tap Magic tapping fluid for drilling as well as tapping. Pro tip of the day is that if your tap gets dull get rid of it. You may not be able to see any damage but it will start to stick and squeal and not cut smoothly. Back out while you’re able and get a new tap, they’re a lot cheaper than the effort and time it will take to fix whatever happens when you snap one off in a blind hole.
