Actually I just went through this same process recently and found that if you apply using the link on Apple's site, you can get the DUNS number for free within 5 days. Follow this form: https://developer.apple.com/ios/enroll/dunsLookupForm.action

I explained the full process at http://blog.metamorphium.com/2012/12/03/apple-duns/

It's sad that this whole process isn't more transparent and easy though.