You said you’re buying from an unauthorized reseller because you don’t want to pay what they ask for. If you don’t agree with their prices that’s totally fine. But then why use their products? You want to use them but you don’t want to pay the developers.
Unauthorized?! It's 100% legal! Maybe not 100% moral, but I needed this for a nonprofit. I donated GiveWP to this and 2 more nonprofits - it costs me $420 per year and it's worth it. But no plugin developer offers a nonprofit discount, and the pricing is just cost-prohibitive. So, I donated the lifetime plan for GPL Vault. Keep in mind, that I could've decided not to pay for GiveWP as it's available from GPL Vault, but because I know it's a complex piece of work... although extremely buggy, I wanted the developers to continue the development and fix those bugs at some point far in the future, but the other stuff is just nice-to-haves and not worth the asking price.