Bought some #24 hose clamps, drilled a #12 hole, and installed some ten dollar K-type thermocouples I bought on eBay. Total cost with hose clamp, about $11 each. In the image is a $44 Westach 712-2DWK compared to the home made unit.
The home brew version has a 5M-0.8 thread. It might be possib;e to drill/tap the exhaust pipe and screw the probe in directly.
See my 8/13/2013 entry for the home made CHT probe.