Facile comparisons between the housing bubble and the current secular bull market in commodities are no substitute for paying attention to economic fundamentals. Your realtor clearly wasn't paying attention to economic fundamentals if she claimed that real estate prices would continue to rise indefinitely because of supply and demand, without acknowledging the extent to which demand had been inflated by the credit bubble (during which "liar loans", no-money-down mortgages, etc. were common).
Commodity prices won't continue to go up indefinitely, and, as Jim Rogers has said, before the secular bull market ends, we will get to a bubble stage, but we're not there yet.