It is it difficult/time consuming to set up a Drupal site that users pay to subscribe to? I have never implemented a payment system in Drupal but it looks like I will have to do it in the very near future. I have plenty of Drupal experience, including writing custom modules, but I know nothing about payment systems.

I know of the Ubercart and Drupal Commerce modules and presume this is the standard way to go when setting up payment system for a Drupal website.

Basically I need to let users pay for monthly subscriptions for the site, and then money will be automatically taken from users' accounts on a monthly basis, until they cancel the subscription or it runs out.

Is this difficult/time consuming to set up? Will it take a weeks to implement for someone like myself with no prior experience in this area? How long rougly would I be looking at to get this set up?
I've just finished writing a multi-tiered subscription system for an online business directory, using Commerce. Without going into too many details (the clients might be watching ;) it took a fair bit longer than a week to complete and sufficiently test the subscription/payment element of the system, and I'm pretty familiar with how payment processors and Drupal Commerce work under-the-hood.

FWIW I took most of my inspiration from the Commerce subscription products PayPal module, which:


  integrates the PayPal Recurring Billing functionality into the Commerce subscription product module.


It's a feature module so you can just chuck it into a site and see what it does (sets up a product type of 'subscription', adds fields to the user and order entities for tracking subscriptions, handles the recurring IPN notification from Paypal, etc.)

If you read through that module code you'll get a good idea of what's required to set up a subscription system using Commerce. If you also need to write a payment processor from scratch then it'd be a good idea to look at the Commerce Paypal module at the same time so you can get a good overview of what needs to be done.

I'm afraid I can't comment on the UC Recurring Payments options as I've never used it.