Black Market Music LA has a ton of used and vintage guitars, amps, keyboards, etc. Definately check it out. If you don't like the prices, make 'em counter offer. Get a return guarantee in writing. They should be happy to accomodate you.
Then head north on La Cienega to Sunset(The Strip) and head east. There's a Sam Ash at Crescent Heights. A little more east past Fairfax there's a huge Guitar Center(with a large vintage guitar dept.) and a handfull of smaller music stores all within a block or two. A nice mixture of new, used and vintage.
ALL of the places mentioned above are within a two mile radius so it's easy to shop around and negotiate a good deal.
If you feel like taking a ride, there's a place called Norman's on Tampa in the Valley with a large selection of vintage gear.
And, as Monty mentioned, the Recycler.