If you are interested in buying brand new, overstock merchandise directly from Amazon (not through middlemen resellers) you can now do so here in the US. The company has run a liquidation auction marketplace in Europe for many years, enabling buyers to purchase from them across Europe. Only recently, however, has the company launched an inventory liquidation marketplace here in the US.
Previously, you had to be an approved buyer who participated in their annual RFP process to contract to purchase certain categories from certain fulfillment centers. It is a rough process because you are required to commit to taking everything in a particular category and the volumes can swing unexpectedly. Now, this has changed. Finally, you are able to buy individual lots via an online auction site. This allows you to buy a limited quantity and to name your price.
The site is very new and will certainly grow over time, but now is the best time to jump in as it hasn't been widely discovered yet. There have been some screaming deals over the last couple weeks. So far it has been footwear, mixed lots, grocery, hardlines, etc., but new categories can appear at any moment.
I highly recommend you jump in and get registered ASAP.