Just got home from a small job - 230 bf (and a 100+ heat index). I usually discuss the economics when someone calls for a small job. I have travelled for a single log, several times. I will explain that the travel fee and setup are likely to be more than the milling fees. If they don't have the ability to load logs, or a way to transport them, I might be the only choice - but I want them to be well informed. Most still go ahead, if they can't figure out a way to bring their logs to me.
I use an 'ala carte' pricing system. Each service stands on its own, so I don't require a minimum time or footage requirement. The Travel Fee is the same, whether I mill one log or 15 logs, currently $3 per mile, one-way. I have a Mobile Setup Fee of $50, which is pro-rated for milling volumes above 600 bf (no setup fee if over 1000 bf). Milling is usually by the board foot, if they need other help, like site prep or cutting logs to length, those are billed as needed.
I offer a free site visit if it appears that they will want milling on-site. I do not "bid" jobs, although I will always make an estimate of their total costs. I don't barter, mill on shares, or "negotiate", my fees. I don't require a deposit or contract. If they lie, or don't appear to be able to follow through on thier end, I'll try to explain (might even do an additional site visit) - or I walk.