underbid me last year on very big job for a high profile multi-purpose real estate development.

I betcha that bid was intentionally low <- they were banking on making the money back via (change orders)

A contractor who built one of the restaurants in the building did something similar. He bid low to get the job and got it. 3 weeks after starting construction he asked the owner for 15,000 check that was NOT in the original contract. Then half way through the job he asked the owner for another 15,000 check , that to was not in the original contract . The owner paid them both.

So the owner was suspicious ? and then asked me if that was common construction practice ? I said absolutely not -> unless there was change orders that differer from the original contract ? Then sure its only fair you then pay for the additional cost.

The owner said there was (NO change orders) at all and thats why he was growing suspicious ? Ahhhh Ha, I had to ask , what was the next highest bid for the project ? He said about 30,000 more <--- (BINGO) you just been Jacked.