Have no problem with € 30/50.- for latest Raknet features working with A6/A7, I could pay more too, but I don't want to because i'd never make anything commercial with Gamestudio. Just want to learn and play as hobby

However I was thinking about how your plugin would work. If it just need the Raknet plugin then its up to the end user to obtain a license for Raknet when used on commercial base. Other non-commercial developers may use the Raknet plugin freely. Sure you can ask money for your work and part of the dll which makes it interface with Gamestudio or would Raknet require you personally to own a license when creating something wrapper like a front end for their plugin and you want to sell that part you've wrote yourself?

If not, you could perhaps create the GUI in a way so it enables or limit some features and ask different prices. Furthermore I don't see why you must pay anything to Raknet if this would be the case. They should be glad because it brings more attention to their product and some developers could eventually purchase a commercial license for Raknet plugin.