Well i would like to suggest some functions to give us a better control over the market system:
1st: Make the current offers list data available(item name/id, amount left, price, etc), plus the possibility to cancel these offers.
Example of use: My script makes a buy offer of 500 X item and 500 Y item, later i run it again to check the market and the amount of both is down to 300, so the script add new offers(and possibly cancel the old ones) to keep the buy amount as 500+ on each item.
2nd: Make the buy/sell offers list data available(amount left, price, etc)
Example of use: make new offers based on information of the ones that are already there.
To my particular use case the 1st one has the higher priority, but of course the second would be nice to use in the future too and combined they would provide a better control over the market.