I own a K-M 7D and typically don't use flash. However I'm attending a 'must record' function that will need flash more powerful than the built in one. In all probability anything I get will then sit in the cupboard, unused, for a long time. I don't know anyone from whom I could borrow a suitable flash.

Here's the question then. What's the cheapest flash that will work on 'auto' on the 7D and give me a modicum of control?

MickLL