Your correct, there is a requirement that they provide you the option of purchasing this option (its really aXXXXXto make sure you like the car)
From the statute
(1) A dealer shall not sell a used vehicle, as defined in Section 665 and subject to registration under this code, at retail to an individual for personal, family, or household use without offering the buyer a contract cancellation option agreement that allows the buyer to return the vehicle without cause. This section does not apply to a used vehicle having a purchase price of forty thousand dollars ($40,000) or more, a motorcycle, as defined in Section 400, or a recreational vehicle, as defined in Section 18010 of the Health and Safety Code.
SO, if they violated this statute, you may have a claim.
The main problem is you are well past the 2 days so they will have an argument that you kept much longer than the 2 days prior to returning. The statute does not state what happens if the dealer does not comply with the statute. You may want to check all your documents to make sure you did not sign off on this.
If not, I would go back with a copy of the law
Copy here: http://law.onecle.com/california/vehicle/11713.21.html
and threaten to sue and report them to better business bureau
and to notify the attorney general
. That and perhaps some negotiations can get them to take the car back most if not all what you paid
best of luck