"If X" "then Y"
there are several places that all the sources such as DBMarket are not quite right. for example many people use the DBMinBuyout to calculate crafting cost. thats is great but sometimes the min auction is some nut that has posted it for 500% below normal price. or its an item with only one poster who priced it 900% over normal price, in these cases the DBMinBuyout will give you a very bad result in your math. there are other situations like this that occur often.
I propose an IF X - Then Y function ...so using the above example. IF DBMinBuyout is below 30%DBMarket or above 300%DBMarket then use wowuctionMarket.
It can be anything like this but basically give us the flexibility to establish parameters to prevent avoid having to use bad data. There are many uses for this type of function