I agree with Ghadeer! I don't know another source except people who speak that dialect!

thanks for your answer Abdulaziz. What is Alafsaha??

The best ALAFSAHA

I guess you can search for the PDF and mp3 files of FSI Saudi Urban Dialect download... Good luck

The best way is to try to find a language partner from KSA because I don't think there are online resources for this dialect. Unlike other Arabic dialects like Egyptian or Levantine for which you'll find many resources like movies and talk shows :)