Create Pop-Up Terms & Conditions page when member logs in and Terms have been updated.

I need to create a page that pops up when member logs into website and it has been determined that the terms and conditions have been updated since the last time they have agreed to them. Dates are stored in a database. Login/logout pages are already created just need to add this routine to the process. Also have simple php/html page with terms & conditions call in it. Criteria: If they log in and need to agree to new terms, the terms pop-up on page (CMS page) they scroll to bottom and re-agree by checking a box. If they close the page or decline to agree, then they are logged out and taken back to index page. Prefer that they are unable to close page. My budget is $30.00 max.