&gt; &quot;I can do it cheaper&quot; implies that I can get my costs down lower.<p>Zero or negative net costs are lower than positive net costs. So &quot;I&#x27;ll do it for free&quot; (or even, &quot;I&#x27;ll pay you for the opportunity to do it&quot;) are instances of &quot;I can do it cheaper.&quot;<p>&gt; &quot;I can do it for free&quot; means that I&#x27;m ignoring any of my costs.<p>No, it doesn&#x27;t; assuming rationality it means that the net costs are nonpositive, not that they are ignored (which would be irrational.)<p>Of course, it could be the result of ignoring some or all costs, but so could &quot;I can do it cheaper&quot; when there is still some charge for the work. There&#x27;s nothing special about the zero charge case.