I agree with Vince. Domestic are ok for flyers (i get maybe 1 call for every 100 flyers

) but for commercial I would put together a little pack with a letterhead, business card, wfp introduction letter, payment options, customer testimonials etc, and go in person to deliver them.
Plus, commercial might be where the money is, but it is a saturated market. Maybe concentrate on the domestic market? Reliabl;e regular WC's are stiull in short supply in most parts of the country.