Welcome to the boards.http://shop.store.yahoo.com/techbuys2003/tm-125.html
Cheapest thermocouple and meter on the planet. Greg has no reason to be scared, but it will measure your average shot temperatures to the nearest degree accuracy. Either make up a schomer style temperature measuring PF (or basket if you have a naked one), or just thread the thermocouple (which is a plain wire) up the spout of the PF and stuff some tinfoil into the PF so the TC stays submerged. The water will flow too fast, but the average reading from 3 ounces of water will be within a degree of what you get using more sophisticated devices.
You will need more expensive gear to get a profile over the course of a shot -- a recording meter and a specially made basket either Schomer or Scace style.
For permanent monitoring, many people strip off the outer insulation of the TC's wire pair and run the two thin wires between the group gasket and the PF-basket lip, attaching the probe to the shower screen. The wire will eventually break (mine always within a week), but some people have gotten a few months service out of the arrangement. The more permanent continuous shot monitoring installation requires drilling and plumbing the grouphead. This is well above my skill rating -- check with Barry, Greg, Andy, Sean, Mosfet, Lino or any other mad machine modders I may have missed.