I know the server guys are busy, but this should be something that they can implement in 5 minutes.
I suppose you have a SQL database for the store and do something like "SELECT * FROM store_data WHERE guild=... AND itemFillter=... LIMIT 100". Shouldn't it be as simple as adding a second function that runs "COUNT * FROM store_data WHERE guild=... AND itemFillter=..." and returns the value instead? Count should not impact performance in any considerable way.