If you compare the prices with the service quality, I would say that it is a fair and affordable price for what the software is doing, and you also can use the adblocker on more than one device. Also, the cost and subscription vary depending on region and currency.
As I said before, you’re not paying only for an adblocker; you are paying for an experience, a much smoother and comfortable experience while you are browsing on the Internet.
AdGuard has a free 14-day trial version when you first install the tool; this will help you to see how the software is working and if the AdGuard pricing is sustainable for your needs. After this free trial, you can choose the ideal subscription for you.