Vistaprint (with an expected delivery date of the 25th) arrived two days ago, and they are brilliant. One hundred cards - with the full-colour book cover image one one side and blurb with two QR codes (one for the novel on Kindle and the other for Kobo) on the reverse - came to just over £30. Which included delivery that came a week earlier than expected.
The postcards are one of the aides I'm planning to help me promote the novel during my time at the Writers' and Artists' Yearbook organised Self-publishing in the Digital Age one day conference on the 3rd November.
There are many tools at a writer's disposal in the field of self-promotion and maybe the postcard is a bit clunky, the fact that it's tactile and has the QR codes on can make it a very useful asset. We'll see but so far it's looking good.