Right now Amazon has the Ladder Boss Pro Tool Bag 90201 for $42.44 (w/ SS shipping).
The Ladder Boss is to the ladder what the Bucket Boss is to, um, a bucket. It slips over the top of a ladder and has an 11-tool-pocket removable section, 4 hammer loops, 4 tie rings, and 3 drill bit pockets. But wait, there’s more! It has a top tray. It even holds a bucket, which you can use to hold more tools. Or Sno-Seal.
The specs on the Ladder Boss site are confusing when you compare them with the Amazon description though — best to assume Ladder Boss has it right.