I wouldn't have a problem paying a LAME $150 an hour............if they knew WTF they were doing, it's that learning curve thingo mentioned above that irritates me. I'm not going to pay an AME or LAME to learn on my plane.
I've had one very good experience with a particular avionics shop on the Gold Coast who was upfront with this very thing. The manager said he hadn't installed the gear and set up I wanted so he came up with a very good price that left something in it for him & me. There were issues that related to billable time down the track that we negotiated. I've also had some pretty average 'got you by the balls' stuff, this has far outweighed the good.
It's not the floor AME or LAME's fault particularly. There's something seriously wrong with this box ticking way of training apprentices. Non aviation trades are a joke as well. You need to park your arse under a tradies stewardship for a period of time regardless of the boxes ticked.