Using a flow meter during forced carbonation

[fstbttms]

The latest issue of BYO has an article advocating the use of a flow meter (or rotameter) to determine when proper forced carbonation levels have been reached. I like toys and this looks like a fun, useful and relatively inexpensive one. Anyone out there using a rotameter and if so, where did you get it?

P.S. My apologies to those of you who will read this on other boards.