I tracked down the cite to the following quote in The Economic Impact of Commercial Space Transportation on the US Economy: 2004.
Recent market studies have shown public space travel has the potential to become a billion dollar industry within 20 years.
It’s the famous 2002 Futron study made public in October 2004. On the bullish side, still no accounting for games. No accounting for $200,000 starting prices (It assumes $100,000) which is bullish for price, bearish for quantity. On the bearish side, still none of the demand flown off. Why am I analyzing 4 year old data when I could be testing the market personally for a little more than the cost of a new study?