Agree with the answer above and once you inform him he has to pay first, I personally wouldn't engage with him any more until he does so. If he doesn't pay, then it is a strike against him. If he does pay, make sure you get your item collection code before he takes away the item (no excuses from him).
And again, it isn't just a case of combating fee avoidance in these scenarios. There were cases where sellers had to deal with aggressive buyers turning up at their home, some wanted to haggle after a price had been agreed and wouldn't take no for an answer.
