I agree with ckcowl, that's the way I do it. In the situation I think I would just go maybe 50$ over my estimate and suck it up. You don't want hard feelings (spoken or kept quiet) at church and like Tartan said learn from your mistake . I worked for almost nothing a few times because of that, you can't expect them to pay for your mistakes. My ex father in law used to say "bought learnin' is the best learnin'" and that's true, you don't soon forget it when it costs you, LOL. good luck, hope it all turns out with no hard feelings.