Can't ship UPS to a PO Box anyway. Personally I don't mind shipping to PO Boxes.
Since it's going UPS you'll have insurance and a good tracking number. The only other thing you could look at doing is having UPS require a signature. I don't know how much more that is, but it might be worth looking at for this amount of money.
Of course that could upset the buyer as he might expect UPS to leave the box on his porch and not require a sig. Just let him know it will require a sig when you e-mail him to let him know it shipped.
If he pays with a MO you don't have to worry at all really. Only real fear would be a PayPal chargeback. I'm in the middle of one of those right now.