What exactly was business? My personal understanding of it was that one party would use an appropriate price to sell an appropriate product to an appropriate customer while trying to obtain the greatest possible benefits.
In that case, since the Onibabas had their own territory and authority here in the Chaos Abyss, what product would they find irresistible?
Weapons, the most commonly traded product in the Chaos Abyss? Some high-quality weapons, then? The Onibabas didn't know how to smith, so maybe they would have some need of this, but actually they were quite skilled at witchcraft and alchemy, along with enchanting.
In this specific area (where the Onibabas gathered) and at specific times (1-2 days every 1-2 months), powerful magic weapons with continuous effects were their most popular product (with most of them being fake), with endless victims ending up scammed.
