The check cashing store has no way of knowing whether or not the check was good. They could have tried calling the bank, but not all banks will verify checks. It's not their fault that the check was no good so you shouldn't be saying that the store should have known it was no good. You owe them the money. Maybe you should try to see about making a payment plan with them to pay back the money. It's not the store's responsibility to go after the account holder of the check, that is your job. You'll have to go after this client of yours yourself. Also, I wouldn't do any more business with this person.
In the future, when you get a check, it's better to take it to the bank the check is drawing off of. If there's not a bank close by, then you should deposit the check into your account and not touch it for about a week just to be safe that the check is good.