Re: Gateway that allows you to hold payments until product in stock?
You can set most Merchant Accounts/Gateway/Credit Card processing accounts to Authorize and not capture until later. Note: there are usually expiration times on the authorization and you may get charged for authorizations that are not captured.
Please do not PM for support issues: a private solution doesn't benefit the community.
Be careful with unsolicited advice via email or PM - Make sure the person you are talking to is a reliable source.