Where exactly in So. Cal. are you ? This will help in guiding you to where you can get the roses you mentioned.
The Princess Diana Rose is sometimes sold under the name "Elegant Lady".
Not all nurseries sell the same roses, so going to their website is a good start.
If you're willing to drive to Fillmore in Ventura County, Otto and Son's Nursery carries the Princess Diana rose. I've seen it in several other nurseries near me as well
I've never seen Jack Frost but that doesn't mean someone local doesn't carry it.
edited to add link