A cheap silicon chip costs one half of a cent.
If the average weight of a bag of UK chips is 400 grams, and the potato commodity price in 2011 is around $174 per tonne, then the potatoes required would cost $0.07. That is, the silicon chip is cheaper than the commodity price of a bag of chips.
For the $0.05 silicon chip, in 2008 on the commodity market, you could buy 180 grains of rice. (2008 was a very bad year for rice prices, at $1000 a tonne. But even so…)
The price of silicon chips has been constant for 20 years. Unlike food, of course.