A surprising few dealers will take him up on the offer, so long as he can be fuckin' discreet about it. Some might find the bike itself a deal breaker because it's not very that (discreet).

But if he does enough favors, he might get told by the dealers that like him that he should give up trying to find where the supply lines break down. Not because it's an impossible thing to know, but because he'll wind up dead if he digs too deep.

If he insists, they'll tell him a lot of the breakdowns happen on the river itself. That's the key to crossing between the realms, after all. Stuff doesn't just "fall off" the boats, either. Someone is deliberately taking things and finding people willing to move the goods into the city.