Belt hatchery is in Fresno.
And yep, Alchemist Farm does have legbars and should next season. They have a few breed to choose from, though definitely not cheap.
Personally Papa's has too many things/projects going on for me. Though I haven't seen any complaints on them.
No, you are incorrect about ALL of CA being warm. Nights get pretty chilly in the hills already and it doesn't get too warm here on the north coast either (max daytime high is 65). Of course So Cal may still be a lot warmer. Then consider ordering from hatcheries in the south. Like Green Fire Farms.
Speckled Sussex are beautiful birds! I personally would wait until next season and go pick them up at the feed store. Biggest problem with breeder chicks is you have to deal with roosters if it's not an auto sexing breed. I excel at hatching roosters and usually get MORE than 75%. Also please note that NPIP does not mean they haven't seen Marek's, mites, lice or other things... which shouldn't be an issue with eggs or incubator hatched chicks.
Good luck getting the breeds you are interested in.