From version 1.1.1 the PRO plugin for Namaste! LMS supports paid signup for a class / group. Configuration is really easy:
1. Make sure you have payment methods set up in Namaste! LMS Settings page
2. In Add / Edit Class page enter your price in “Charge X to sign up for this class” box. You need to have selected “Allow users to sign up for this class” checkbox first
3. Use the class “sigup shortcode” shown on the Manage Classes / Groups page. Publish it on a post or page and the paid class sign-up will be handled automatically.