Don't claim to have a ton of experience, but I had a good experience with Pasadena Firearms. Average price, good service. Seems like most of the shops in the area don't want to do transfers.
I've done one with 2A sales and supplies in Jessup. It cost 50$ there I was seeing if there was anything cheaper. That price is better then some I've seen but always looking to save a little if possible. I'm looking to transfer a DD MK18 Pistol.