You can set a button on your page that, if clicked, starts rendering a HTML page to PDF - only that the page you're asking it to render is exactly the page the user has clicked the button on. Once you got the PDF you can just send it in the normal way.
This of course requires a program that can render arbitrary HTML pages to pdf. You might want to check out ABCpdf which has always worked for me like a charm, but it's not free.
