How do you answer this?

I was related a story this morning that I found really funny so amidst the doom and gloom of everyday life in south africa:

This actually happened in Holland where a South Africa couple were staying for a while. One morning they woke up and the wife asked the husband to go and get some food for breakfast and gave him 30 guilders with which to buy it. On the way, just around the corner in fact, he walked past a prostitute who gave him some 'come hither' looks and fancying himself as a bit of a player he entered into a conversation with the woman. After a bit of chit chat he got down to the nitty gritty and inquired about the price - 100 Guilders was the answer and so the bargaining began. She dropped her price down to 80 and he was offering 30 and eventually she asked how much he had at which point he opened his wallet and showed her the 30 guilders. "30 Guilders, I won't even do a hand job for that!" she retorted indignantly and they both went their separate ways.
A week later he was leaving his flat with his wife on his arm and they walked around the same corner and lo and behold, bumped into the same prostitute. "See what you get for 30 Guilders" she commented as they walked past.
Now, I ask you. What exactly do you say to your wife at that moment that isn't going to result in celibacy?