Money arguments are a pain

We’ve had some house repair work done, one big job (replacing the front deck and installing a wheelchair ramp of sorts up to it) and three or four small ones (mirror clips installation, under-sink particle board replacement, fence wind damage repair). The estimate was $1,730 for materials and labor.

The jobs are pretty much done. Along the way we’ve paid out $1,443, $743 for materials and $700 for labor. There were some additional materials purchased which weren’t in the estimate, and that’s fine, we’ll pay for those. But the guy threw out $600 as the amount he thinks he should be paid upon completion, about $300 above the estimate.

I don’t think I’m particularly cheap, but it frosts me some that somebody underestimates what the job will cost and then assumes that the buyer will pay the difference with no argument.

I should say that we’re quite happy with the work he did. It’s now a sturdy deck again and when it’s fully painted it will be attractive (it is now completed):

Am I wrong to feel that way?