What’s a fair price for asphalt sealcoating?

I manage a small office building in Denver and our parking lot is due for sealcoating this spring. I got a couple quotes and they’re all over the place: one was crazy cheap and another felt way too high.

A property manager friend recommended Asphalt Coatings Company. He said they did his lot last year and the price was reasonable for the quality he got.

What are people actually paying per square foot for professional sealcoating in the Denver area these days? Is $0.30–$0.45 normal or am I getting ripped off?