This isn't California specific, and I was never a California lawyer (thank the good Lord!), but as a general proposition, enforcing a contract by forcing the other party to go through with it is pretty hard to do. That's called "specific performance", and historically it was only applicable to real estate transactions. That's not always true, and I've seen some specific performance contracts which were enforced regarding personal property items.
More often, damages are the only remedy, and typically they are measured by the amount of the loss incurred by the innocent party. Since we're talking about the losses of the buyer, the only usual way to measure that, is to have the innocent party obtain a similar item elsewhere, and the "guilty" party then has to pay the difference between the agreed price and the price the innocent party had to pay.
An example: XYZ Motors agrees to sell Clem a new Ford truck for $28,000. But when Clem goes to XYZ to pick up the new truck, they won't go through with it. Why? Well, perhaps the salesman made a mistake and the selling price should have been a lot higher, or maybe XYZ's owner's wife wanted it. Whatever reason, they won't sell it to Clem. They hand him his down payment and tell him to get lost.
So Clem goes to ABC Motors in a neighboring town, finds the same truck with the same equipment, and buys it for $35,000. His logical damages would be $7,000, the difference between what he had to pay and what XYZ had earlier promised to sell it for. But especially because the same identical truck was available at ABC and perhaps other dealers, it would be nearly impossible to get specific performance and force XYZ to sell that particular truck to Clem.
On the other hand, if a vehicle was truly unique, one of a kind, it might be possible to get specific performance. The first Corvette, the first Shelby Cobra, or maybe the only remaining supercharged 1938 Mercedes SS with all matching serial numbers. Things like that might persuade a knowledgeable judge to grant specific performance.
On the issue of verbal agreements, every state has statutes that fall into the category of "statute of frauds". That doesn't mean a real fraud. It means that there are restrictions on verbal agreements. For instance, there may be a minimum dollar amount, or a particular type of agreement, which requires a writing. If a statute of frauds requires a written agreement for that particular transaction, that means that a verbal agreement is not enforceable.
Certainly the cost of litigation is a major issue, too. In the last decade of my practice, I used to tell clients that if the most their case was worth was in the $20,000 range, it wouldn't be worth litigating, even in County Court. Some wanted to do it anyway, and often they were shocked at the cost, even if they won. The real losers are those who can't afford it at all. The case might be worth only $15,000, for instance, but both sides are likely to spend more than that on attorney fees and expert witness fees.
That's why Small Claims courts were created, to handle lesser cases. Here in Colorado, I understand that they've fairly recently raised the limit in Small Claims to $10,000. No attorneys generally, and much less adherence to the Rules of Evidence. But not slam dunks, either.
Now don't anyone blame the messenger. I didn't make the system, but I learned how to make it work for many of my clients, but not all. Often there were ways to persuade parties to do what they had promised to do, legitimate legal threats that were persuasive. But not always.
Cary