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.