The question remains that if large numbers of people are willing to pay $20+ per btc in a mass market environment, why is the Bitcoin community going by a price set on an exchange populated by a relative few comfortable traders, bots and people trying to move their .573 btc fortune?
Because it isn't a large number of people. Price discovery is the aggregate of all buyers and sellers. Just because a tiny (i.e. rounding error) of trades occur at 50%+ over the median price doesn't mean that is the "true" price. Even if you want to say "exchanges are too hard and don't represent real price" in our fastcash4bitcoin service we have bought over 80,000 BTC and on average pay about 4% LESS than MtGox. For someone looking to sell coins for "cash" it is about as easy as it gets. Fill out a web form, send coins, get some cash. On the other end you have BitInstant selling coins for ~5% over MtGox price. I don't know if they publish any sales volume numbers but my SWAG would be in the hundreds of thousands of BTC.
So here you a group of users who for one reason or another don't want to use an exchange and the prices ranges +/-5% (maybe +/-50% in extreme cases) of MtGox. 50% over is simply an outlier; outliers happen but it doesn't mean you should throw out the 99.5% of trading data and focus on the 0.5%.
More than "true" price ebay selling for >50% over MtGox simply shows an inefficient market. In a free market sellers should attempt to get the highest possible price. Competition is low on ebay and that means higher margins, if volume grows more sellers will join and that will drive down the prices. Still he seller isn't getting a net price of 50% over MtGox. Part of what you are seeing is the transaction cost. Some back of napkin numbers, say seller loses 20% in fraud and ebay/PP fees are another 10%. So even with no profit the markup would have to be ~30% over MtGox.
