Owners review change order pricing line by line, so price it the way they read it. Start with direct cost by type: labor (at burdened rates), material, equipment and subcontract. Then add markups in the order your contract allows.
Self-performed work usually carries overhead and profit (OH&P) at the contract rate. Subcontract work usually carries a lower GC markup, because the sub's quote already includes its own overhead and profit; some contracts tier it so larger sub amounts get a smaller percentage. Insurance and bond costs are often added last, as a percentage of the subtotal.
Two things keep a change order from stalling. Back-up: quotes, quantities, time and material tickets, and a clear tie to the event that caused the change. And consistency: the same markup rules, applied the same way, on every change. A reviewer who finds one inconsistency will re-check all of them.
Sample data: CO #14 on Riverside is $78,100 of cost (mostly a $68,000 sub quote from Summit Mechanical) plus $8,300 of markup, for $86,400.