Gold Coast Steel in Oxnard, You'll prolly talk to Ivory (the tricks some parents play in their children)
Taylor Steel in Oxnard stocks DOM tubing, but I think it's 1018 not 1020.
Ventura Metal Supply & Ventura Steel; one of these is on Stanley Ave (first exit off the 33 from the 101), the other is really close to the RR tracks on Eastman in Ventura. Can't ever remember which is which. The one on Eastman stocks Aluminum and stainless too.
If you're really hard up for non ferrous alloys, try ABC Metals on the 101 frontage rd 1/2 mile south of "PJ Grunts" (don'ask) and two big blocks south of Costco in Oxnard on the same side of the fwy.
Might also talk to DeNunzio's about this. They may know of more local sources since they're in SB.
"It only seems kinky the first time"
-- Bumpersticker seen in Lost Wages
Ventura Steel is on the corner of Ventura Ave. and Stanley. Their inventory is mostly structural iron and some tubing but no DOM or 4130. Ventura Metal Brokers is on the bottom of Eastman. They do have some aluminum and stainless but they should offer you some vaseline with each purchase as they tend to expect a premium for everything. They will order in anything you want if you can afford their prices.
Most places in LA and Orange counties deliver to Ventura but probably not SB. If you want small quantities of 4130, call Aircraft Spruce in Corona. Their prices are reasonable and they will ship it. If you need a lot, make a trip to Industrial Metal Supply in Burbank or maybe Tube Service in Santa Fe Springs. Otherwise, Taylor steel in Oxnard or Gold Coast Steel in Oxnard may have enough to satisfy your requirements.
Thom, was that your truck in the parking lot at PJ's?