I think you should ring around, and just try out workshops. Stop listening to everyone because everyone has their own experience and loyalties about certain workshops etc. Get some quotes and try maybe a few mods here and then a few mods there.
From there, based around your OWN experience you can decide to either stay at one workshop or move on to another... Its all good hearing that one place is great to this customer or that customer, but if your not happy how does it matter?
About the whole money issue, well you will have to be prepared to pay for the quality of work in which it entails, but once again try various workshops and from that you can judge which one was money best spent.