I have been following up on this project, all good contractors follow up on their projects.
An itemized list / cost breakdown, more often than not is used against the contractor when it is shared with other builders who will then beat it.
Good contractors use good people, and good people cost more. Just the cost of having the appropriate insurance / bond can be the difference between winning a job or losing it ot a 'lower bid'.
It is the rule of three; there is Good, Cheap and Fast. You can have any two: Good and Cheap, won't be Fast; Good and Fast, won't be Cheap; Cheap and Fast, won't be Good!
When comparing bids, it isn't the cheapest or the 'nicest' person you should select. You should understand why there is a large price difference (it shows there are gaps in your design program or what you have asked for specifically, which means there may be arguments later). If most of the bids are in line, and one is way high or way low, you want to know why before dismissing or selecting them.
A price-only decision almost always costs more in the long run.
Good luck!