Just took a look around their site. The prices do look almost too good to be true but they are probably importing everything directly themselves which is why the prices are so low. That being said, they may have had supply problems in the past which is what they could be referring to. I've been to places like this before in the City. Just a huge, unorganized warehouse that deals mostly with the trade.
Depending on what you are ordering, it might be worth a shot to save so much. I'm thinking about picking up a couple of things and seeing how they do. I would try them for such a good savings. $3.00 is not too much. Besides, you might spend more than that just getting to Joanns.