You should be able to find them at most nurseries. The big box stores typically carry a selection of Australian plants (Grevillea Noelli, Grevillea Red Hooks, Callistemon "Little John," Callistemon citrinus, Eremophila... etc) If you want a wider and more specific selection, you'll have to find a specialty nursery, which I'm sure there are plenty of in the area. I live in Northern California and we have a large selection of Hakeas, Grevilleas, Corymbia, Eucalyptus, Doryanthes and many, many more at select nurseries. Southern California will have even more availability I'm sure. I know Australian Native Nursery in Ventura specializes in Australian plants but it is too far away for you unless you'll have an entire day to spare. Good luck! Welcome to the Golden State!

I wouldn't have classified this as a succulent, either, but it is definitely a cool looking plant that is not that common. The same species is available thru some wholesale nurseries such as San Marcos Growers out of Santa Barbara, so you can find it outside of botanic garden sales. I've seen it growing in full sun, well drained and low water gardens here in the San Francisco Bay Area, also, but it doesn't tend to be long lived unless it has perfect drainage, and full sun. Tip pinching to renew it and keep it from getting rangy or too woody also helps, as does a pebble mulch to keep the basal stems drier in winter.

Nitrogen draw down is a significant problem for your vege patch that contains 'hungry' shallow rooted annual, biannual and short lived perrenial plants. But even here you can compensate by liberally sprinkling blood and bone over the soil surface before laying the green mulch.

Goodness, you couldn't get further from a Eucalyptus, could you? It looks interesting, but wonder how the seeds got so mixed up. There are still some suppliers for Australian native who do seed in small amounts, (not all do mail order overseas, or they charge for a phyto, or have a minimum order amount) but sometimes they may be more reliable depending on what you want.