@Tae Seung Kim I know it's been a while since you posted this, but I wanted to respond to help anyone in CA reading this thread. I always use the California Association of Realtors (CAR) purchase agreement for all my deals. I am also a licensed broker, so I realize not everyone has access to these forms. Yes, this form does not allow for assignability, but I have yet to meet a seller who will refuse to sell to someone else with the exact same terms they have already agree to...your mileage may vary!
The standard inspection contingency is 17 days, meaning that you can back out for almost any reason, with no liability and get your deposit back. However, if you remove contingencies in writing (they must be removed in writing in CA), you are typically only liable to lose the actual amount of the deposit. I have been doing this 27 years, and I have seen hundreds of people back out of contracts, and so far (knock on wood) no one has ever lost their deposit who backed out before contingency removal, and no one has ever lost more than their deposit for backing out later. I am sure there is a RE attorney who would have an exception, but that is my experience.
Good luck to everyone :-)