Bingo.
From your own observation, we can conclude that high commodity dollar prices are basically a result of the depreciating US dollar i.e. devaluation.
And a devaluated currency goes hand on hand with inflation.
Therefore you cannot rule out asset price inflation as the explanation of high commodity prices.
from Wikipedia
http://en.wikipedia.org/wiki/Devaluation
Generally, a steady process of inflation is not considered a devaluation, although if a currency has a high level of inflation, its value will naturally fall against gold or foreign currencies. Especially where a country deliberately prints money (a usual cause of hyperinflation) to cover a persistent budget deficit without borrowing, this may be considered a devaluation.
