Got my invites all figured out and ordered and I went very unique with the RSVPs. I used VistaPrint to do my invites and RSVPs. I used the cheap 1 sided Invitations and uploaded my own design. Then I used the free business cards for the RSVPs. I spent a total of $89 for 150 invitations and 250 RSVP cards (FREE)!!!!! Free envelopes!!!! You can't beat that.
I even went as far as creating a hashtag for our wedding stuff!!! That way when friends and family upload their pictures they can just put in the hashtag and it will make it that much easier to find.