... As far as determining whether the bid is fair or not. W/O being able to see the type of cabinets and countertops you have, and the 'profiles' of each, it's hard to say.
The best thing to do is get 3 bids. A few things to keep in mind are: 1) If you get a bid from a place like Home Depot or Lowe's, you're price will include a kick-back to the 'middle man'. 2) There material used for refacing and countertops vary. Make sure your bids state the brand of material being used for BOTH. 3) When you get your bids in writing, the only way you'll know who's the best for you is to ASK the bidders why you should pay more (or less) for them to do the work. Tell them you have bids that are more (or less) than theirs.
Different contractors charge more (or less) for different reasons. Maybe they're NEW to the business. Maybe they don't actually do the work, and someone else does. Maybe they use better material. Maybe they're just real good.
It's best, IMO, to get completely new countertops. DON'T have your existing laminates removed and re-used unless a new substrate is installed over top the 'old' glue. The glue from your NEW countertops won't bond well with the 'old' glue. Also, one way I figured my contractor was good was he made his templates IN MY HOME and didn't have to take them to his shop to re-make them. That's good! And that type of contractor is out there! In this case, you don't have to have any type of 'temporary countertops' installed while your new ones are being made. Also, Some folks may differ but my seams are at the sink. If it's elsewhere, you'll easily see where 2 sheets come together. I, personally, am not worried about the seams leaking. Why? My installer has been doing it for 35 years, and #2, you get what you pay for. As an aside, a couple of days after the install, one of our counters was 'rocking' a little. (That's because it was installed on just a wall; not on a cabinet-top where there's support on 4 sides.) Anyway, it wasn't a life-threatening situation but he did come out a few days later to reinforce it. Soooo, he 'stood' behind his work.
Others may have more to offer. My best to ya and hope this helps.