Your card is saved securely through Stripe, never charged up front. Money moves straight from you to the shop only after the buy succeeds.
Join at $4,232 and the group hits 10? You get billed $3,956. The tier you joined at is a ceiling, never a floor.
If the buy does not reach 5 kits by the deadline, no card is ever charged. No refund request, no chasing an organizer for your deposit.