Does the shop offer any other no charge incentives? Example: free software upgrades as they become available?
What kind of Lead-Time should you expect? Long lead-times are not necessarily bad. If you are shopping and find some shops are quoting 3 weeks and others are quoting 3 months, one may want to consider why one is so much busier than the other. It may be a reflection on the quality of work performed. Patience on your part potentially can pay off in dividends.
What kind of Down-Time should you respect? Reasonable down-times are ok, excessive down-times are bad but bear in mind that the projected down-time can be related to the quality of work to be performed.
I find the cost of installation labor is the largest diversity between shops. The cause of this is not usually the labor rate or expertise of the install technicians. It generally is mostly impacted in the quoted number of hours associated with the task which is directly proportional to the answers obtained from the above questions. A difference of $500-$1000 can be seen simply be reusing old wires/cables.
500-U Airport Road, Lititz, PA 17543 · 717-569-1953
Does it make sense to install, for example, a new GPS/Nav/Com which costs you $7000, is your #1 Com, your #1 Nav, maybe your only ILS, and your only IFR GPS, only to have a shop cut the wires from your removed 20+ yr old system, strip those wires, crimp on new pins, and connect them to your new product just to save $1000?
Reliability can work hand-in-hand with safety. It was heard somewhere that a consumer looks at three things: Quality, Price, and Time. Of these three, the consumer can demand only 2 of the 3. Try and apply this to your situation and see how it suits.