Add a speculated calculated loss.... Itemize that item on your bid, and see how that goes down.
Just plain ol' overbid what you could loose by jacking up the mark-up. Spread that through the bid. If they ask why you are so high, tell 'em its adjusted for inflation.
Or get the project awarded, purchase the material, and not take delivery until needed, and require payment for the mats right then. Or, in some states you could qualify for lien by just having the matierial dropped on-site right then... (If the project ever starts or not...) Don't forget to add the APR of that money to your bid right from the get go... (As if it were still in the bank....)