Got to agree with Tom and Michele. Portraiture is a "service" industry and people want you to go that extra mile. If the commission is anywhere in my state, I don't charge for travel expenses. To me, this is part of the service I provide. I have done several commissions out of state and we have been able to meet once when the client was here and then do everything else by phone, website and email.
The distance commissions do require extra communication on your part to let the client know what is happening. I usually create a client-view-only webpage on my site for the portrait and I take periodic shots of it as it progresses and type messages to them. Every time I update the page, I send them an email to let them know to go out and look at the updated page. It works pretty well.
