LewRockwell.com's Michael Rozeff Says Gold's Not In A Bubble

He says so on the basis of his Zero Discount Value (ZDV) model, which assumes that gold will be remonetized. According to the ZDV model, gold should be selling at about US$7,725/oz: that would be the price if every dollar in the U.S. monetary base is backed by gold in the U.S. Treasury's hands. The divergence between the ZDV forecast and gold's current price is ascribed to "[t]he vagaries of the market."

Near the end of the article, he mentions central bank buying:

In the present situation, a tipping point seems to have been reached in which major players like India and China are moving away from dollars. Japan has not done this. Japan is still buying dollars. The momentum is shifting away from the dollar. Central banks have started to buy gold. There has been a turn in the tide. There is no tidal wave, although one could develop. Reversing the tide seems increasingly unlikely.

If you believe in the premise behind the ZDV model, or are just curious, Prof. Rozeff's explanation of it is worth a read.