I'm adding a simple transactional element to a client site to allow their users to pay a bill online by completing a simple form with a payment amount and a bill reference. Payment will be handled by a payment gateway via a POST.
However I'm unsure what the best practice might be in terms of storing this data on the EE side.
In the past I've used the Solspace Freeform module to capture the data, re-display it on a confirmation page and then use that to POST the data to the payment gateway.
One other option is to use a SAEF to submit the data as an entry and do much the same after that.
Which to do... the benefit of using entries is that they are more flexible - the disadvantage is they cannot trigger a notification email to the user and/or client but that can be handled with a simple plug-in if required.
I'm interested to know how others have handled this in the past. Specifically in a scenario like this where an e-commerce module would be complete overkill and the Simple Commerce module isn't an option.