I create 2 accounts on any of a number of bitcoin exchanges, I put in a sell order at a high price using one account, and then I buy the exact amount of coin at the high price with the other account (No one sane will buy my coins at the high price, so I can even let the sell order sit for a few days). Now do this 10,000 times per day with bots (exchanges have APIs), and you get a price graph that looks similar to the current exchange rates...
The problem is that there is no way of specifying that you want to buy your own overpriced coins. The exchange will match your buy order with the cheapest sell order on the exchange.
You say "No one sane will buy my coins at the high price", but the truth is that no one (not even you) is *able* to buy your coins at the high price until they have bought all the cheaper coins on the market.
Was that hard?
No, but it didn't work.