I want to know all or at least a good representation of websites,
services, or tools out there that provide a feature whereby users can
put in target prices for a goods/services to affect driving the price
down based on aggregating demand.  For example such a system would
know that current demand for product "A " is 100 units per day at a
price of $1.00, and users would input their target prices & qty for
things they want, based on their flexibility.  From the users input,
the system would analyze that demand and know that it would rise X% if
the price dropped by Y%, allowing the seller to adjust the price if
they wanted.