listed histories for prices can be heavily abused by RMT.
If they have any form of history it shouldn't list individual transactions at all. Instead it should be an average of the last... 20 sells, Ignoring changes in price that exceed between 15-30%.
So lets say an Item sells for 40-60k Steadily for 18 Times, Making the Average around 50K. If someone sells one for 100K or 10k That change wont reflect in the history, and prevent RMT's from being able to manipulate the price quickly.