Email additional info to buyer after purchasing certain products?

I want a product to display instructions (a message to the buyer) after they buy the item. How can I do this?

I know I could edit the code and add an ifcheck against the SKU in the email code, but is there an easier way?

Not that I can think of off hand ...

A products_purchased_message table with the product_id, product_purchased_message_title, product_purchased_message_text, product_purchased_message_html would work ...

You could even extend that to be multi-language if needed ...

I used both the title and the message as text and html separately for either admin management or flexibility in the email ... the text/html could be the same without anything special on the html emails and just be shown as text ...

But I digress ... As the email is built, the message could either be added right then, or the message(s) could be added at the end of the email ...