While I certainly understand price shopping, it seems to me that in this business it could drive you to drinkin'!
There are many factors that determine what contractors charge for their services. While there are fairly standard square footage install rates for many services in most areas, most of what is involved in a rehab is priced per man hour required. Some contractors use estimating software, some estimate based on their experience thru tracking over the years, and other pull figures out of the air.
By far, the best way to nail down a realistic figure on a rehab is by scoping the job and putting hard numbers on each step of the process. Even then, the contractor must base his numbers on a known quantity... A crew he has tracked long enough to know how long it typically takes to do the given work.
And then, there's the estimate vs. bid issue. If you are soliciting bids, you end up with a contract for the work specified. Its a hard number you will pay even if it takes longer than the contractor anticipated. An estimate is just that, and could be more or less. Some get a warm and fuzzy having a hard number bid to reduce the unknowns, but generally end up paying more for it. Contractors are no different than investors in that they dont like to loose money. Even the best estimators add a percentage to their numbers to cover their butts.
My point is that price point on any given service may not be all that important a factor when one looks at the big picture. Most important is building relationships with contractors with whom you CAN feel "comfy". Here are some characteristics to consider. Other may have more to add...
1. Does he consitently deliver the quality craftsmanship youre looking for?
2. Does meet agreed upon deadlines?
3. Does he play well with others? Budget, deadlines, and quality can all be significanly impacted if there is not good communication and cooperation between subs.
4. Does he routinely provide you with a rundown of the potential problems that may be encountered as the layers of the job are peeled back? An experienced contractor, Has seen it all, and will want to eliminate as many potential surprises as possible. If not offered, its a good idea to get in habit of asking contractors what the possible hidden problems could be and what they will cost if encountered. Example: tiling bath floor... What if there is rot in subfloor from leaking toilet. How much to cut out subfloor and replace. Know there numbers in advance and figure them into deal numbers. If not needed, its gravy!
4. Does general Contractor have his own crews or does he sub most of work? Generally speaking, he has more control over time and cost if he run his own crews. However, an established GC whose been using the same subs for years and who keeps them busy so that they are available to meet his deadlines is a good bet.
Personally, if I didnt do the work myself, I would look for an experienced remodeler who does it all. A guy thats gotten over chasing the buck and has downsized to a small crew who does high-end work. He's running a lower overhead than a GC and will likely work with tighter margins in order to work with an investor who knows and understands quality and is willing to pay a fair price without constantly being taken to task over the nickels and dimes. He is also loyal to those who appreciate all he has to offer that a price isnt put on, such as problem solving skills, knowledge of proper material selection for any given applications, jobsite oversight and leadership, conflict resolution, layout and design advise, etc.
A solid craftsman has so much more to offer than just "labor". If you want the best bang for your buck... Focus on the big picture and develop a working relationship with a details guy who will have your best interest positioned right along side his own.