The idea
A group buy collects buyers before production. The more buyers join, the lower the price per unit, because shops quote lower prices for larger runs. When the count reaches a target, the run starts and buyers pay.
Why a saved card, not a hold
A card authorization holds funds for a short time, often days. A waitlist can run for months. So a waitlist should save the payment method and charge it once, at the trigger. Buyers pay nothing until then.
Where group buys go wrong
Quotes expire. A price promised months ago may no longer hold, so quotes need to be re-requested before the trigger.
Charges fail. Cards saved months earlier can be declined or need the buyer to confirm. A plan for retries and for a run that starts at a lower tier is part of the design.
Dates slip. Parts run short and shops fill up. Buyers should see a ship date before they join, and be told early and offered a refund if it moves.
Quality surprises. A part made by one shop can fail at the next. Serial codes and a clear rule for who pays for a bad part keep the dispute short.
A note on rules
In the United States, selling goods ahead of delivery comes with rules about ship dates and delay notices. This page is general information, not legal advice. Get legal review before you sell.