Tell me, please, how to make a page with photos of the product, the "buy" button and a description?
The question is, what do you need for the blog engine, to make crutches to make a shop. There are engines for shops use them.
Great plugin WpPage You can try for free for 7 days. I really liked it, the design is easily done, the side columns are removed and in general everything is superfluous blogging, buttons to buy, etc. etc. are available.
The easiest way is to use additional fields, if you understand programming, it will not be difficult for you to do, all the more convenient, you can customize any settings you need, just read the manual (code) on how to install and display additional fields. Ie, without any plug-ins, and unnecessary functions, you will turn your post into a page with the product, its photo, description, and additional fields, such as price, color, anything you can add and display there. Well, if not, and you need something for more, then only special plugins. The type of "woocommerce" which is very useful by the way. But if you want to make a full-fledged store, then use such CMS systems as OpenCart, Magneto, PrestaShop, Ecommerce