It is still possible, but MAGIX Online Shop at the website sells only the latest versions of the software, currently v.19.
See Products menu at https://www.vegascreativesoftware.com/us/ (or or your area's version of that URL, including "de", "gb", "ca", "int" etc.) for the purchase and subscription options. (Choose a "payment plan" from the dropdown menu at the site's Online Shop.)