Thanks for the sign link!
Being a traffic engineer, I love signs, especially old ones. I found a fenced in building and lot in Phoenix that has a TON of old signs (from Phoenix) I'd love to get my hands on. It's like the perfect "american pickers" lot, but the owners don't sell anything.
Aside from street signs, there are old stop signs and warning signs that have the old "cat's-eye" marble reflectors, just laying around. Those things go for a lot of money. Do you notice any of these type of old stop/warning signs with cat's-eye marbled reflectors still in existence in LA?
(in that lot I saw an "S Curve" sign, a "Slow" sign, among others, just like the above pictures).