Hi and welcome to the forums. £2.20 is the standard cost of sending an average book, though anything less than an inch thick (when packaged) will go for the much cheaper large letter rate. However, I don't think £2.20 is that bad really - most of the charity shops round here charge almost that and have a much more limited choice in most cases than RiSi does, plus now you can send even quite heavy hardbacks for £2.20, which is actually cheaper than it was to send them last year. I've received quite a lot of new release hardbacks as swaps which I think is an absolute bargain! And as you say, although you have the effort of wrapping up and sending off your book, it does also help you to keep the numbers down as you get rid of one for every new one you get in!