I would be more likely to buy 20 packs of 5. Out of the 100 cards they would contain, it would be likely I'd get a set. Plus , if you randomly insert setch cards in the packs, there is the chance of getting one as well.
The thing is, if you package them as $1 items...and it costs you the same as if you packaged them as sets, you would have a greater chance of selling 'em all, since a dollar to most people isn't much...but $24 is something they have to think about.
That said, however, I would purchace a set for $24 if that's what you wind up doing.