My fault. I just edited the post and put the link right at the first instance of the product name.
I gotta link to the broader product page because every click generates a unique checkout link. So I can’t provide the direct link to the checkout. (Don’t worry, it’s completely free. The checkout page simply exists as the delivery method.)
Also working on a standalone website. Ideally that’s what I’d link to, but the website’s not finished yet.