Again the problem I see here is the damage. Under contract law, the damage has to be real. Mere speculative, future, contigent, imaginary damages can not be compensated. Emotional distress and mental trauma can not be compensated. The second time you had the free will and choice to choose an agent, the $15k paid to the agent may be real damage to you, but it is not going to be recognized by law. Under promissory estoppel, the legal detriment has to be reasonably foreseeably relied on. This buyer has no reason to know or should have reason to know that you were going to hire an agent, so that he is probably not liable for that. The double mortgage and equity loan may be considered, if you can prove that you had no other alternative but do that. It would be a strong case if at the time of signing the contract you had other offers but turned them down so that you incurred loss. Based on what you said, I have no doubt the buyer acted in bad faith. The damage, however, is just too small for any lawyer to take on the case. You can go to small claim court to try to get some money back. Again, I would investigate the contract carefully to see if there is anything about offer revocation. Seven weeks seem really long to me. In California, buyer has 17 days to back out of a contract after signing and no questions asked. After 17 days there is some penalties, such as losing deposit. I am not quite sure about the statement the law only protects the buyer. The law protects mutual assent of economic interest, including both buyer and vendor. Except that you had a pre-approval letter from a bank (I assume you had a copy before signing the contract), other things are either weak or irrelevant, such as they did not want $1000 back, because the jury needs to speculate on them. Whether these things are material breach of the contract is up to the court to interpret.
Equity court does not normally award penalty for breaching a contract. To punish them, you have to bring about a tort action for breaching a contract, to show that they intentionally interfered with the contract performance which resulted in legal detriment. Tort courts will allow damages for emotional distress, future damages, and punishment.
Look at the contract carefully to see if there is any arbitration clause. Some of the real estate agents are also arbitrators who can help you settle the case without going to court. Besides, they know more about property law than I do.