I'm working on grabbing prices from multiple exchanges, and I know with things like EtherDelta it's far too easy to place an out-of-order trade way beyond the reasonable bid/ask range. So for an application to represent the accurate price, we can't go with the *last* price. Should we just present the latest bid? The average between bid and ask? The last closing trade that also is still within 10% of the bid/ask?