We had a pretty wide range of estimates for our house, and there are so many factors that I would hate to give a guess. Depends what kind of shingles you want, the status of the roof deck and other factors. I would get several estimates and check several references for the ones that seem reasonable (not necessarily the cheapest, though, mind you. There was a company that gave us a really low bid, but they were clearly not reliable). Here is some information I wrote up a couple of years ago about choosing shingles:
And here's another article that answers your question a little more thoroughly:
Sorry I can't just give you a number, but hope this info helps. Also, for your climate, consider a white or at least light-colored roof. It can really help with power bills and do your part to combat global climate change.
Really depends on your market, the condition of your decking & flashing, and what you are going back with. If you only have one layer of roofing, you can overlay the roof with another layer of shingles. How old is your home and is this the original roof?
Roofing is sold on the square...which is a 10'x10' or 100 sq ft per roofing square. In our market, a basic install runs from about $150 to $240 a square depending on who is doing the work and whether you are using normal 3-tab shingles or architectural shingles.
Also look at you venting - you may want to install a continuous ridge vent which will add some to your costs if you don't already have one.
Andy is right it all depends on the product you select and the removal of the old roof adds to the figure as well, keep in mind when selecting the product you desire look at other roofing suppliers as well other than Home Depot or Lowes. Sometimes you can find really good deals out there due to this sluggish economy.
How much would a 4 door car cost? There will be a wide range of answers. The same is true for a roof. How steep is the roof? How many layers need to be torn off? What is access like for loading materials? What is access like for removing debris? What are the details of the roof? What steps will the roofer take to replace the roof? Is the permit included? What quality of product do you want installed? Add to that geography, the type of company you may choose to hire (handy man with a truck and ladder or professional roofing company), there simply are too many variable to ever price a roofing job site unseen.
I disagree with the comment about the light color shingles helping with the electric bills. It won;t help much at all. Air Vent Inc, in conjunction with the University of Illinois did a study back in or about 2001 I believe. The goal was to determine this myth, if it was true or false. What they discovered is that on a PROPERLY VENTILATED ATTIC SPACE the heat transfer was minimal, something like a 2 degree difference attic temperature. While the shingle surface heat was well over a 20 degree difference white to black. See yes black does hold heat, but attic ventilation is more important than reflectivity when you have a "cold deck" design, as must shingle roofs are cold deck meaning the roof is ventilated and the ceiling insulated.
As for deals, be careful! The person installing your roof will figure out a way to make money, and if he is offering a deal it will be at your expense. What is he neglecting to install? Is he giving you a deal by installing another layer of shingles over the existing. This lay over method may be allowed by code, but is rubbish! Always tear off the roof. Is he offering you a deal by reusing your felt paper or maybe installing 15 Lb.? Again garbage, opt for a sturdier felt like 30 Lb or fiberglass reinforced or synthetic. Yes it costs more upfront but will last longer. Will he offer you a deal by reusing your flashings? What good is it to replace a shingle roof, but reuse components, we replace all flashings on all roofs period because the roof is a system neglect one component of the system and the whole system fails. Will he offer you a deal by neglecting to improve your attic ventilation? Most attics are under ventilated by today's standards, and are under ventilated by shingle warranty requirements. Don't improve the ventilation and you have no, or have reduced, shingle warranty.
Learn more about the shingle roofing system to make sure you don't out smart yourself by taking any deals: http://www.reliableamerican.us/services/shingles.htm . Expect to invest more upfront for a longer lasting roof, period. Afterall it costs more to install two cheap roofs than one good roof.