Using Paypal to collect payments is probably the quickest way to get a startup up and running. Even for recurring payments paypal works quite well. In fact for

Using Paypal to collect payments is probably the quickest way to get a startup up and running. Even for recurring payments paypal works quite well. In fact for users who already have a paypal account, signup would be easier than entering credit card details into a form you host. Also I think there's a better chance your users will keep their credit card details up to date as they'll be using their Paypal account for other things. e.g. ebay.