You can try:

http://jhpusa.com, they are in South El Monte, I have ask before and they have quoted me around $ 3,900 for my DX. They're pretty reliable, no bullshit.

or

http://www.racelinedevelopment.com, they are in Temple City, they quoted me $3,800
but 2 days turn around time. Ask for Elton Lo, he's a great guy and does engine swap very quickly. Straight to the point as well.

Let me know if you can find a cheaper and more reliable shop.