Building an online store requires a lot of different steps. From securing the site, finding the right commerce software for design, handling the transaction (creating a hassle-free checkout experience), figuring out the shipping logistics, SEO and analytics and finally marketing efforts.
When I built my first e-commerce site in 2005 and sold my first product online, it was an amazing experience. Today, selling online is the standard. There are so many different website builders out and what it comes down to is what one feels comfortable with.
I built my first e-commerce site with a software called MonsterCommerce. It was very clunky and you had to know ASP to build it. Its customer service was pretty bad. The checkout process also had too many steps, which is why we seemed to have a lot of "product left in the cart." I used OsCommerce for my second store and I liked how easy it was to use. I built the store and turned it over to the owners without any problems. For my final store I used Magento. Magento's admin is incredible and the checkout process and bank transaction were a breeze. There were limitations, like shipping issues (they ship by weight, not by dimensions, which meant it was very expensive to ship certain items) but if I was going to build a e-commerce site, Magento is the software I would use.