I've recently discovered another GPL store that I like and want to share with you: https://www.gplvilla.com
Besides the "classic" collection, I noticed that they store has most (or all?) major Oxygen builder plugins available.
I like that you can buy lifetime updates for single plugins, and they are inexpensive. The site also offers monthly and annual memberships.
The update speed is decent. When a plugin had not been updated in two days, I contacted them and support came back to me within a few hours.
So far, I can fully recommend this GPL site.