I did a search but most of what I found was about doing it and the tools needed not about people who do it.
For us, what we use are manifolds to connect together multiple inert cylinders as a fixed fire extinguisher. At the moment we use a 1.5" pipe with welded on inserts to join them together (pressure tested to 90 bar) but we are limited to 5 ports as they seem to distort too much after that. With flow drilling we can use a single length of 2" pipe with flow drilled and threaded inlets with around 20 ports on a 3m length, no distortion, more accurate spacing and less chance of leakage.
I bought the kit some time ago (as well as upgrading our drill - a normal pillar drill doesnt have the feed rate and RPM necessary - i needed to buy a small radial arm) for a job. Its pricey but worked out cheaper in the long run than subbing it out.
When i was doing a bit of ringing round, there are a lot of fabricators out there who have the kit and offer it as service to people/companies.
We looked into it first off but weighed up cost of 5kw drill suitable tap the bits to do it well and pressure test (this is shady as we would be testing something we make ourselves) it's pretty much a no go at the moment. We already need to buy a bigger bandsaw and a 3" threader as it is.
I suppose i should mention we need a pipe thread ISO 7 RP 1" in a 80 schedule pipe so its not your usual flow drilling.
At the moment there is one place that will do it at an acceptable price (actually cheaper than the welded version) but it would need to be shipped here from denmark, which would limit us to 3m lengths instead of the preferred 6m