"Selling" Your Book for Free - Will it Work?

I've been toying with the idea of giving away our book for free. The only problem with that is that most things are not really valued if they are free. I was thinking about this the other day and came up with another idea. This is the idea: charge for the book, then offer to give a refund after it has been read in exchange for a short review. I would then have the option of publishing (or not) those reviews on my website or blog.

I wonder whether this would actually work. Do any of you have any ideas?

What got me thinking about this was that I just received a free e-book recently that sounded very, very interesting. But I wonder if I will ever actually get around to reading it. Hmmm...

I also signed up yesterday to get the free e-book version of Robert Kiyosaki's latest book along with the option to comment on it and "help" him write it. That one I might actually read.

So what do you think about "selling" your book for free?