This article is from the Macintosh for sale FAQ, by Elliotte Rusty Harold firstname.lastname@example.org with numerous contributions by others.
Remember that the salesperson needs the sale more than
you do. The more time a salesperson spends with you the more
pressure they're under to justify that time to their sales manager
by selling you something. Hemming and hawing over the price
(especially if you haven't told the salesperson how much you expect
to pay) can often lower it. You can ALWAYS get a lower price than
advertised. Aside from the prices in this list a good idea of when
a salesperson is genuinely giving you the lowest price can be had
by noticing the level at which they have to check a price with
their sales manager.