if you are commission based, do the trick fymk said, push her
the most expensive thing and challenge her wealth, since she talk
big, make her "buy it or admit you cant afford it".
If you dont get commission by selling products, then you can do
other things, things that you dont break the rules as a staff. I
mean you can be scarstic, but reamain polite at the same
time.
She ask for your manager right? say to her nicely "Just a minute i
will ask my manager to come." The shout(shout to your manager, not
to her) as loud as possible so that the crowd can hear you,
"Mr.XXXX, a very rich lady who drives a BMW is looking for you,
please come over!" You are doing it as she requested, you was not
rude to her, so she cant complain you.