Add 2 upsell images and links to 2 checkout pages

I have a php custom membership site with 3 membership plans. If a customer chooses the lowest plan, I would like the customer to see an upsell offer image and link for the middle plan on the next page, along with a "no thanks" link. If the customer chooses the middle plan, I would like them to see the image and link to the highest plan on the next page, along with a "no thanks" link.