FFG SWRPG mechanic payment costs

In an Fantasy Flight Games Star Wars RPG Campaign:
For various reasons I want to pay a random NPC mechanic to perform an attachment modification check on my weapon instead of my character doing it himself. Assuming I supplied all materials and supplies what would be a expected base cost for his services (assume Core World legal establishment ~Rebellion era).

This comes up because my GM has a GM-PC droid which I “own”. He forces me to pay said droid any time I want him to do anything (including mechanics checks). This is sometimes way overpriced for mundane things like this, which is fine because I can just find another mechanic somewhere on a world somewhere. The mechanic will then charge me an even more ridiculous amount with no negotiation forcing me to use “my” droid. I need proof of correct base amounts to show my GM to clarify what the mechanic should be paid, regardless of what the droid demands.

Thank you.