Prohibition on increasing prices for one who does not intend to buy the product

If a person increases the price of an item that is offered
for sale when he does not intend to buy it, this action is haraam, because
it involves cheating and deceiving the purchaser, as the purchaser may think
that the other person only offered this price because it was worth it, and
that is not the case. This is the artificial inflation of prices which was
forbidden by the Messenger (peace and blessings of Allaah be upon him)
as it is haraam. It says in the hadeeth of Ibn ‘Umar (may Allaah be pleased
with him) that the Messenger of Allaah (peace and blessings of Allaah
be upon him) forbade artificially inflating prices. And it was narrated from
Abu Hurayrah (may Allaah be pleased with him) that the Messenger of Allaah
(peace and blessings of Allaah be upon him) said: “Do not go out to
intercept the riders (for trade), do not outbid one another, do not
artificially inflate prices, and no town-dweller should sell on behalf of a
Bedouin.” Agreed upon.  

If it is proven that the price was inflated artificially, and
there was some deceit involved in the sale that was out of the ordinary
(i.e., some cheating in the price), then the purchaser has the choice
between cancelling the deal or going ahead with it, because that come under
the heading of being given the choice in the case of cheating. End quote.