So I have posted in player ideas a mechanism to counter market manipulation a thing I found some time ago while I was testing something in the market.
Here is one example you can do.
But you can also change average price, lows, and highs, and volumes.
From ccp’s side they currently actually can’t realy do much about it other than manually delete data input done by someone if there are sure someone is manipulating the market like that and if they don’t want that.
You can experiment with a lot of things like luring bots, or just shake a market for the lulz
(edit: forgot about sales tax, changing high’s and lows is for most part free)