WOW!! cost keeps rising!
I have been doing some research and I think I have narrowed down what you will need to run a TQi system with telemetry...
Temp sensor and mount
RPM sensor and mount
RPM magnet and spur gear mount
Voltage power tap (i think this is optional)
these items are scale specific but you can add them to the 1/8, nitro and 1/16 scales too.
roughly 45$ for the aforementioned parts
and if you want the GPS speed - GPS module and expansion module to accommodate the extra plugs
OH, GPS is around 160 if you want to add that
lets not forget the I device and app
If I have forgotten something or am incorrect, please correct me