$15,000 is fair for a basic e-commerce site. Not for the one you have displayed though. It is cheap and tacky.

I let clients know they are looking at $12,000 and up minimum, most run!

The reasoning behind the high costs is that an e-commerce site means ANYONE can set up a business without even having to lease or own a bricks and mortar store. The lease or ownership of a bricks and mortar shop can run into the high tens of thousands.

When you consider the above, you realise e-commerce sites priced at $15,000 aren't that bad.