The cost of a website mostly depends on the amount of time required to build it. To give an estimate of costs for a website, your web designer needs to collect as much information as possible so they can estimate the time required to build the site.

You should know you are not forced to hire a web designer to get your website published. Nowadays it is easy to set up a store with easy site builders provided by web hosting companies (WYSIWYG: What You See Is What You Get). There are many web hosts offering such easy tools. If you compare best web hosting sites reviews you will find hostgator, Godaddy, Bluehost, and Yahoo Small Business are the most recommended companies. Especially Yahoo is a great choice because they offer cheap web hosting, email hosting & domain registration services and let you pay monthly your billing. They even have made creating a website easier with offering various templates for any type of store.

To get more info about the prices and services offered by Yahoo Small Business refer to:

https://smallbusiness.yahoo.com/webhosting

After all, according to my personal experience, selling via ebay is easer than your own website. Marketing and getting traffic for your website will be a big challenge.