Many of these websites sites selling protected lines are
shysters.

One common scam:
Some of them will advertise a product on the website,
and once it is ordered, then they try to determine how
they can obtain it (grey market or whatever). Even if
they can get the product, it may take a while. In the
meantime they charge the customer's credit card and have
use of the money.

If they can't get the product, they then try the old bait
and switch.

Another scam is advertising a product for a ridiculously
low price on internet price comparison sites. The product
advertised is a loss leader. Once the customer orders
it, they get a phone call from a high pressure salesman
selling accessories/extended warranties etc. If you don't
buy the sales pitch for the additional items, the original
item is mysteriously unavailable.

There was a whole thread over on the custom installers
board about a group of websites, linked to the same company,
which does this very thing.

You might try checking audiophileliquidator.net on the
BBB website, if there are complaints against them you
could forward the info to your client.

There are gobs of websites advertising protected lines
for sale, but just because they are advertised does not
mean a customer can actually order and receive the merchandise
for the advertised price.