First, don't ever sell bitcoins on the exchanges. Instead, look hard for ways you can spend it on things you need.
Isn't the difference between buying currency rather than goods, using Bitcoins, mostly philosophical? Otherwise, I can't see a difference.
FWIW, in Europe a lot of EUR prices fluctuate according to the USD exchange rate, since the importers need to pay in USD. Computer parts are an obvious example, the prices can change a lot over time.