One thing to keep in mind is that a quote is a fixed amount, but an estimate can be changed. Insist on a quote being issued to you.
Compare all three quotes to see if they are similar and are the prices on all of them similar?
If one of them is massively cheaper than the other two that are quite close, has he listed the same works as the other two?
If he has, ask yourself why he can do it so much cheaper. Is he going to use the same quality material? Never rush into a decision, consider the pros and cons of using the cheapest if he is vastly different. He may be inexperienced at pricing, or he may be completely new to this type of work.
But if you end up having to call someone in to put things right, it will not have been the cheapest option after all.
As Harry the Handyman says "you get what you pay for" - your three quotes should all be within approximately 10% of each other.