I got 3 quotes from general contractors for a tenant improvement project, all 3 were given the same design. Honestly to me it seems like a pretty straight forward project overall, my real estate agent thought it would be in the 50k range (he used to be in construction and has family in construction) Separately my architect said its a pretty easy project, thought it would be "well under 100K."

First contractor: $120,000
Second contractor: $46,000
Third contractor: $220,000

Of note, the 3rd was the recommended to me by my agent, the other 2 were the highest rated contractors I could find in my area of AZ who have at least 15 years of experience, a lot of positive google reviews, great record with BBB, etc.

Pretty crazy - the highest quote was almost 5x more than the lowest quote, with the lowest one being pretty close to what both my architect and real estate guy thought was a reasonable fee.