How can I enable a pre-payment option for a raffle on my ecommerce app?

[CherMonsieur]

Hi there,

I'm about to bring my idea to life with an app together with shopify integration. 

One thing which is still unclear to me is the payment: The idea is that customers buy limited products. If they want to buy, they enter a raffle and hope to be lucky to get the product. By entering the raffle they need to pre-authorize the price on their credit card / paypal / ...

Customers who where lucky are then deducted the full amount, while the unlucky ones don't pay. 

Is there an app or something on shopify who enables this?

Would be awesome if someone knows a solution to that 🙂

Thanks in advance and cheers from Vienna