Why it's good to go shopping in foreign currency (if you're stingey)

Simple - you aren't focussing on the price, because to understand the true price in your own familiar currency you have to convert it; and for most people that conversion has to be done in their head; and for most people, that'll be the first mental arithmetic they'll have done since primary school. Salaries may not be much, but they're a darn sight more than pocket money.

(and "for most people", read "me")