This is a common item from many bikes.

The cheapest available is for the Hysong GT650.

https://www.hyosungspares.co.uk/products/hyosung-gt-650-gv-650-aquila-throttle-position-sensor?_pos=3&_sid=340d4de23&_ss=r 

This is the exact mikuni twin bolt part as on the Peg. Be careful not to get a single bolt version, that one won't work.

Currently, £45 although it was £35 I think they sold so many they thought it best to raise the price!

Here is a useful post from the forum
https://www.apriliaforum.com/forums/showthread.php?343046-TPS-trail&highlight=tps