I mean you let it open with your preposal so the team could also create a rare (or better) card.
I think if you get 5$ discount by buying a node with a voucher the card should be at least rare and not common for one voucher to really add a interesting oppurtunity, I mean if the card is rare you can also say 1 BCX with 1 Voucher for every 3.000 SPS to reflect the differences in the BCX you need to create a max-level-card.