I just checked the codex pricing page, it's pro 5x for $100, pro 20x for $200. The 20x plan has a codex usage boost until the end of may, whatever that means.

Edit: apparently the usage boost is an additional 2x for both 5x and 20x. So maybe it's time to start watching whichever of these services is currently doing offers like this and switch subscriptions every few months.