Tallguy, I start on rentalcars.com, then compare the prices on Price Line with the pop window and look for the inefficiency in the system. When I checked this morning the best deal I found was $22 for a full size car at the San Jose airport. Just keep hitting it every day and find the sweet spot and besides it doesn't cost anything to reserve a car on rentalcars.com. I think at the Oakland airport you should be able to find some great deals, but its pointless at SFO, there always out of cars.
Some tips:
weekend rates start after 12PM on Thursday
5 day rental is usually the same rate as a 7 day rental
when you buy the cheap gas option at the car return you still get hosed because they add a hefty airport tax on top of gas charge unlike the gas outside with the built in tax on the pumps.
This is my rental reservation to show you its not hog wash. The airport tax was $2 less than my rental
Tony