Add eCommerce options to Drupal website

Hi, I have existing Drupal site with hundreds of articles. At this moment, users have to be logged in to read whole article – if they aren't, only part of article is visible. This is built on Drupal panels – using different views for logged and anonymus users. I want to expand this feature: - every user see only first part fo article - premium users can seee whole content I think the best way is to integrate this with shop module (Drupal Commerce or Ubercart?). This way we can sell: - premium membership for selected time (like 1 month, 3 months, 6 months, etc – it should be definable) - points to be used for reading single articles If user is buying premium membership, system should assign him "premium" role for chosen period (and revoke it after his membership expire). If user don't want to buy membership, he can buy some points (in predefined sets, like 10 points, 50 points, 100 points). Then, when he opens article, he see shorten version and may decide to spend one point to read full article. This article should stay open for this user forever (flags?) What's very important – payments should be integrated with payU ([login to view URL]), using their API: [login to view URL] or SDK (whichever is simpler). Within this project, new payment system should be prepared in mirror of the site (I'll give all necessary access to this mirror environment) and implementation instruction must be delivered. There is no need to adjust CSS to any design - it must be as simple as possible. Any CSS will be added later. Please let me know if you have any questions, and bid only if you have an idea how this could be done. Thanks!