Welcome to the forum.
The 686 only comes in one frame size, called the "L" frame. I believe you will have to choose between 4" & 6", not 5 & 6. Can't help with prices in So Cal, never bought a gun there. You'll just have to go price them and see what they run. Most dealers, except big box stores, will negotiate with you - just bring cash.
If I were you, I'd find a local dealer to do a transfer for you. Bud's has the 6" 686 for $647 including freight. Bud's might also have an FFL in the So Cal area already on file that they could recommend. http://www.budsgunshop.com/catalog/p...ducts_id/26249