I installed a Luftmeister temp indicating dipstick in 1990, it will surprise you, on how hot the R65 engine runs in the desert heat Rich !!!
I'm not so sure how accurate the reading is, because when the engine is running, my best guess would be, that the only oil that gets on the dipstick would be 'splash' oil, not oil sitting in the sump, and whether or not it would make a difference on a 'true' temp reading on how hot the oil is.
As far as price, you're probably not going to find anything for a less costly price, I paid $90 for mine 18 years ago.