We ended up not using the handmade paper ones because I found invitations I just loved. I got a sample in the mail and decided to make a mockup myself in Photoshop. The wording isn't exactly correct, but the quote IS what we're using (since we love The Princess Bride).
The hearts and the text are all printed in silver using the Bickley Script font. The envelopes are lined in silver and the return address is printed on them. The RSVP cards match.
Here is a photo of the actual invitations.
These were all ordered from Ann's Wedding. The invitation style is F10852 - Silver Hearts.