I've also seen a very rare punctured float, and a less rare split diaphragm, but the only reason jets or needles ever need replacing is if the bike has been tuned. These parts don't wear. They just get obstructed with dirt. Needles will usually need to replaced if the diaprhragm's split for the simple reason that the diaphragm and slide come as an assembly and are sold with a new needle that isn't really needed.

On FI systems, the TPS and often the stepper motor are integral with the throttle body. Replacement cost is several hundred dollars - 700 - 800 typically on a twin cylinder bike. The TPS, basically a carbon track potentiometer, is a common point of failure on many bike systems.

Rob