Does anyone know if/where I can get Avery-type postcards with postage already on them?

Question

The kind that you can print in your printer and then separate into individual postcards becasue they are perforated...

Answer 1

Avery doesn't sell postcards with postage already on them, although the post office does.

The post office has a program that lets you print postage yourself. (you have to pay) You may be able to use that with blank postcards similar to what your describe.