Huh I didn’t even know the RC took plasma donations (assuming you’re not talking about blood, like the other commenter mentioned). But yeah, you can sell your plasma to other companies.

The Red Cross does great work, though (I donate blood to them as much as I can), so it’s not like you were donating it to some shady company at least.

If you don’t have an issue with needles, you could donate plasma. Believe you can go a couple times a week and it’s around $50 per session. Takes about an hour each time you go.