How does bitcoin's price volatility compare to commodities/stocks with comparable market capitalizations? Bitcoin's long term (after 21 million units have been created) market cap is about $102 million. 

Price volatility of individual commodities/stocks is inversely correlated with their market cap, so price volatility is to be expected with bitcoin, but relative to commodities/stocks with similar market caps, does it have a volatile price?

I'm guessing that price volatility for bitcoin would be low relative to commodities and stocks with comparably sized markets because it has lower transaction costs allowing for a more liquid market, and I'd like to know if the data shows this to be the case, but I don't know where to start looking as I'm not very familiar with commodity and stock markets and trading.
You wrote: "Price volatility of individual commodities/stocks is inversely correlated with their market cap". There is just a coincidental correlation between the two. Instead, I would say that there will be price volatility when investors are unsure about the value of an asset. You can see this with the value of for example Facebook. It is just very hard to judge the value of their assets, regardless of their huge market capitalization. Similarly, the value of Profit Points (which I invest heavily in at the moment) will heavily depend on the expectation of future profits of Open-org.com. On the other hand, one has government bonds, which have a very stable value, because it is relatively easy to calculate their value and there is usually not large risks involved. 

Just to be clear about the value of Bitcoins... 
If you buy Bitcoins you get a share of the future output of the Bitcoin economy. 
You can see the master himself (Warren Buffet) explain this here. I believe that it is hard to judge what the future output of the Bitcoin economy will be, but it will be easier and easier the bigger the market capitalization of the Bitcoin economy, so for Bitcoins there will be a correlation between the two, but other factors like risk of government crackdown will also affect the volatility.