If you find a map in the Map Store, but want to learn a bit more about it, right-click on the map and select Open in a New Tab. This will open a new page that displays the title, description and other metadata for the map. As well, at the bottom is a web map with the map extents, as well as 3 scaled previews of the map to give you a better idea of what the map looks like before you purchase it!
As well, from this page, you can click the See all maps by Vendor hyperlink at the right side of the maps. This brings you to the vendors landing page, where you can see all of the products this vendor has to offer.