The approach I would recommend is setting up a pro account with White House Custom Color lab. They have very good rates and they will mount and or frame the prints and drop ship them for you to a customer of yours. Go to WHCC.com.
A big advantage is that your customers can pay extra for a coating or gallery wrap or special mounting or framing and WHCC takes care of it for you.
They will let you send in 3 images and send you back 3 prints at no charge so you can verify your computer's settings are correct. Even with B&W prints there are color tones. With WHCC you have the option of going to paper using a special laserjet process that is close to darkroom and provides the most durable prints or they can generate inkjet prints (which require more protection of the surface).
For pro's they provide special services and if you need information or assistance you can talk to a real person and get help fast.
Files I upload on a Sunday are shipped out on Monday to customers who have them by Wednesday.
