Omega is a very broad line distributor, and rarely all that cheap.
Over a pretty wide range of Reynolds numbers - IIRR from about 3000 to
100,000 - vortex shedding flow meters are just as good, and
mechanically simpler. I don't know how cheap or popular they are - I
worked on one in 1973, and was mightily impressed, but I've not kept in
touch with the field since. Google produced this - the second out of
14,600 hits.