You can do that at Zazzle. Here is one of my invites: Miami skyline at night panorama - Invitation The preview always looks a bit hazy but that's only the preview. The print is fine. Get 10% off custom invitations with coupon code: INVITATION10 You can also chose from 6 different types of paper.
Do you use a professional printing service? Usually they offer that. I use Miller's and they offer all of that extra stuff. If you're not a business, Mpix.com is 'consumer' site.
I googled it. Didn't really find what I was looking for. I looked at Mpix. Didn't see the front and back option. Maybe I over looked it.