Hey Randy,
It's pretty hard to get a straight answer on this forum (not that you can't get good advice -- it's just seldom the advice you asked for). :-)
In short, I don't think you can rent crampons if you're coming from SoCal, but if you could, the two places that would have them would be the Whitney Portal Store and Elevation (
http://www.sierraelevation.com/, located in Lone Pine).
If you're coming from Los Angeles, then I don't know of any shops that rent crampons that are in the city. Crampons do wear (and if they're steel, you can resharpen them, but only so much), so they're not an ideal rental item the way an ice axe is.
You can buy a decent pair for a bit over $100.
The previous posters have good advice. Basically, don't do anything stupid.
As for whether you need them, I haven't been to the area for a while and can't say.
-Stephen