The only thing I can see it doing (by my understanding) is that they will post the sale on a separate site, and the trader has to keep a tight updated observation on their stock count. It could be the case of 2 shoppers on different sites want to by the same item, both made a bid for "1 available" and the trader would have to prioritize who gets the last item. I see it more of a customer service and tradesman protocol change than anything else, so price shouldn't be the affected numeral.
If I had 10 of a products, I'd split it (50% each or 30/70%, which ever site sells best) and add the numbers onto the site that way. At least then you'd have a certified flow of stock on each site, rather than one batch you need to keep tabs on.
Edit: Ah, should read it all before I say anything... lol.
I dont know... the dropping of the "minimal charge" limit could be a lot of reductions, but will that effect other products from the same vendor? If one item outsells another, they may not let the other product go down for a long time after the fad has fled. So we'd have one item selling out and restocked etc, and one stagnant product - and that's not good if it's an indie/unique title and you're interested in it.