That big of a difference is kind of nutty. Remember, though, these are just quotes, and you will actually end up paying time and materials. Unless the contract has a cap at X% above the quote, you could end up paying a lot if they lowballed the estimate to get your business.
+1 on recommendations, even if it's something like Angie's List or Yelp. Look for things like the estimate being close to what people actually paid.
Good luck!
2001 Cannondale R500 <3
2011 Specialized Ruby Elite Apex
2021 Tangential Speedarama