You can download a trial copy. If you like it, you can purchase the license and upgrade your trial copy to a full version. This product was so good in beta, that as soon as I noticed it, I bought it over the web and am now a very satisfied customer.
One interesting thing - I ordered the product for over the web download and activation, with a US$ credit card, but with a UK address. The site charged me VAT (at the correct rate of 17.5%). But when I entered my VAT number (I'm still VAT registered) and the VAT disappeared. This makes it easy - no VAT to pay or recover. But I like FeedDemon enough that I'd have paid the VAT inclusive price.
The joys of trans-national e-purchasing!