Cheapest place for thank you cards?

[iiTTCii]

I'd ideally like ones where I can add a photo.

 

[biglebowski]

We got really nice photo thank you cards from photobox. They look like a photo booth strip with 3 photos on the front. You can add a little message on the front and a longer one on the back. We got 20, with envelopes, plus postage for around a tenner.