I had an advisory seat reviewing bids and change orders on an interactive sculpture installation at LACMA. The installation contractor tried to change-order the museum for site protection and dust control that were missing from its own approved bid, and it implied a very expensive number.
Instead of negotiating the price, I read the contract and the code and used the contract's own fine print.
Contractors sometimes leave out things you assume are included, then bill for them later. This contract mentioned site protection vaguely, but enough.
The claim failed, and the museum paid nothing extra. That one, we won.
Before you argue about a change order's price, check whether it is a change at all.