Check out Red Star Military on Washington Blvd. in Culver City. Ask for Ian Shein or Loren. They charge the lowest of ANY store in the area and give you NO hassle about processing the PPT. They like to do the private transfers because it brings people into the store to buy other things. They only charge the state maximum for the PPT ($25 ?), and they don't tack on any erroneous fees.
You will get a cold shoulder at most shops in the CA. SB-15 created a lousy situation for dealers preventing them from selling most of the used guns that would come into the store. I've been in stores numerous times where the squeaky little guy afraid of his anti-gun wife or the old widow selling her husband's collection, came in to "sell their guns" to the gun dealer. Dozens of times, that "old unwanted gun" ended up being something like a mint Colt 1911-A1, 1950's Colt National Match, or perfect condition early Browning High power with several Hi-cap mags. Or the wimpy guy buys an H&K P9S back in the '80's, never shoots it and wants to sell it for $300.00, because hey, like a car, it has depreciated? (the H&K P9S is a real example).
Of course dealers will still buy these and sell on-line or at shows, but it kills part of the pure profit and the lesser deals where they would have still made $100 - $200 on a used Colt Python bought for $550 and sold for $650 - $700 for fast turn around are now few and far between. Used guns and private transfers have been cut by 50% in CA for fear that if you sell it, you may never find one again. Postings for handguns in CA on Gunsamerica have become very limited. If it is something special, prices are escalated beyond reason (because of the idea you may never find that SIG P210 for sale again). Much of the used stuff out there now is junk or well-worn. In some cases, dealers couldn't give it away. And if it is rare, people are asking for the moon.
Often a dealers only recourse is to sell new "tupperware" guns and draw bigger commission from wholesalers and Manufacturers.
However, there are few exceptions. Red Star Military likes to do the private transfers because it brings people into the store to buy other things. They only charge the state maximum for the PPT, and they don't tack n any erroneous fees. 11018 Washington Blvd. Ask for Ian or Loren. Plus it is a very interesting store selling all kinds of items having to do with shooting and militaria. They have some real nice stuff and one of the few stores that caters military rifles and cowboy action too.
Just across the street is Martin B. Retting, another gun store, however they do not accept much by consignment anymore and seem to have the disdain mentioned earlier (like Turner's) for doing PPT's. I think they charge some additonal fees too, not sure on that. In any case, they are right across the street from Red Star. Honestly, dealers don't make any money on the transfer, so if you do a PPT, it's always a nice gesture to buy a couple of boxes of ammo or some nifty new gadget he's got in the store.
Your best bet is Red Star.