Choosing the right roofing company can be a scary process, will the company be con men will they do a good job etc! The best thing to do is to get a few quotes and to check reference of their previous work to make sure they can do what they say they can. Even if you have to view their recent work in person. Parting with that kind of money is a big thing and a roof that is done poorly not only looks bad but can be very dangerous.
Costs of Roofing services
The costs for roofing can vary alot depending on what you need doing, you may only need minor repairs doing or you may want an entirely brand new roof. So the best thing to do is to have multiple companies come out and quote you so you can get an idea of what it should cost and it should help you weed out the companies that are overpriced. Although being overpriced should not make you rule them out completely as the saying goes you get what you pay for, so don't completely eliminate the most expensive quotes because at the end of the day you want the best work doing for the price you can afford.
References
All companies should be able to provide references of previous work so make sure you as for a few and if they refuse then it probably safe to say that they aren't that good.