If I put out a buy order and put in a value higher than existing qualifying sell order (range, etc). It should iterate through existing sell order and buy at that price. This could prevent the problem of forgetting a decimal and accidentally purchasing some item for 100X the real value, which is a horrible experience exacerbated by bad game mechanics.
Also, if there are bunch of small sell orders, and I want to consolidate purchasing them all, why should I have to click on each one and buy the specific quantity, over and over. I should be able to do a big buy order, but pay the sell price.