It was a mistake (a kindly one but a mistake nonetheless) to hold merchandise without a deposit in the first place. It worked once but didn't work the second time. You have learned a valuable lesson that you probably won't repeat.
And really all it cost you was some time assuming the goods aren't seasonal.
I don't expect that trying to collect money from him now would do anything but stress you out. In any business there are some customers you simply don't want. This is one of them.