I haven't organized one of these, but I've been a part of garage sales with multiple sellers and I would think some of the tricks we've used would work for you:
Each seller prices their own items; they each need a code to add to the price sticker to show it's their item (we just used initials). Everyone checked out/paid at a single location and at that spot, we pulled off the price sticker and added it to the seller's tally sheet. Then at the end of the day, we just totalled up everyone's $$ and paid it out.
Now, these were sales that included maybe 5 people at the most and not a lot of $$$, so it won't be so easy with a larger group. If you have it at a location where you need to pay rent, you'll need to decide a fair division on that (if someone's only bringing in a few items, should they pay the same amount as someone who's selling a small store's worth of items?). And you'll also need to be sure that the person or people working checkout are trustworthy. It would be pretty easy to just lose a sticker here and there, if you know what I mean.
Thinking about this some more, I think I'd want each person who was selling to have an inventory list of what they brought to the sale and what they were pricing it at, just as a double-check at the end of the day.
~~Cheryl, with a "C"