Hi cparrott. You could try one of our Trade book formats, as they're going to be the least expensive option: http://www.blurb.com/trade-books.
It's worth noting that any print on demand book, whether it's ours or a competitor's, will usually be more expensive per copy than a book printed via offset printing. That's because offset printing (the method used for most mass-produced books found in bookstores) requires a minimum order of 500-1,000 copies. This brings the per-copy price down but requires a large initial investment by the author. (If you're interested in offset printing we do offer an offset option for large orders).
Print on demand, on the other hand, needs only a minimum order of one copy. The smaller scale and different workflow results in a higher cost per book but there's no large financial commitment for the author, since we print books only when they are ordered. So while the cost is higher per copy, you also don't need to invest thousands of dollars to see your book in print!
I hope that helps clear things up and that you don't let the price difference stop you from putting your book into print.