A niche is a distinct segment of a market.

For average joes like most of us will probably not be able to compete directly againist those online superstores like walmart with their cut throat prices. This is because they purchase inventory in extremely large quanitys, enabling them to get it for a much lower cost.

So instead of trying to have a website with as many items at possible,
for the lowest price possible. You should emphasize on a niche
market targeting specific pool of audience only. Provide good service, make
your site appealing to your niche market and give it a bang that is give it
a unique feel to your niche market. This can increase traffic and more importantly
build customer loyalty. The key to make their visit an enjoyable one. ^_^

For Example, you can sell games only. Or if you want to go even further you can
sell only RPG games. Design your website that will be appealing to RPG fanatics
by having attractive banners and buttons related to popluar RPG Games.
Give a little extra bang to your site, by having a blog where you rant about all
the RPG goodies, or have a forum for your users to discuss RPG games with each other.
There are numberous ways to increase your customer bases, so be creative.
Remember, even though price is important, it is not the only factor! There are also
other ways to win over a sale!