As far as I can tell, the only pre-existing item (or something similar enough) that Albert and Rufie would be able to get in the Nine Hells would be a lock of hair from a succubus. A Demon Heart would be a close second, as I believe the Hells are the habitation of LE Devils, but of course that would require porting the item over from BG2. And both of these items would be utterly useless except for sale at Feldepost's, but then again, so is the Bandit Scalp, pretty much.
Optimally, I'd just keep the Bandit Scalp and tweak Albert's dialog to omit the "more where we're going" part, which might very well be just what Idobek is doing.