How many days does the buyer have to submit the earnest money before it becomes breech of contract and if it becomes breech, what can be done?

I put my home up for sale By Owner and received an offer from a wholesaler, that I accepted. The buyer drew up the contract, chose the earnest money amount, selected the title company, and demanded I remove the sale ads. The buyer then hesitated weeks to hand over the contract to the title company so after speaking with the title company, I turned it in myself. We are 3 weeks from date of signed contract, and less then 4 weeks from closing date. Buyer still has not submitted earnest money, is trying to lower the price, stating he does not have an investor, and said the home does not meet value although there has not been an appraisal or walk-thru of any kind. I do not want to alter the contract or sign a new one.