Negotiating handyman project that went over budget

[Anonymous]

We hired a handyman to complete a few projects around our house. Turns out that without telling us, he purchased more supplies that we feel he should have included in his original estimate. We think he's going to hit us up for the whole bill. Is there any way to negotiate this? We went back and forth on the price, came to a final total we agreed on and and are a little taken aback by the extra $500 in added costs.