My fiancé has been making our invitations, if any of you have the time and inclination to do this you should, because it will save you a fortune:
50 cards and envelopes = £10
Lino= £4
Ink= £6
Total= £20!
Each card is slightly different because they are all hand printed, I love how organic they look! Here is a link to some instructions
http://www.apartmenttherapy.com/how-to-linoleum-131394