£16.99 for a bit of curved plastic 
there must be something else out there.
I bought a set on the 30th April 2007 and they cost £18.00 then on an introductory special. They come in a pack of 3. I bet the postage to send those won't be cheap either - they are quite big. The price also has to include the cost of tooling to make them which is very expensive.
If you think those are expensive then look at these;
http://progutter.co.uk/4 shaped plastic tools for £50.00 without adaptor and pole. But they are worth every penny and they make cleaning gutters manually so much quicker. They paid for themselves with the second gutter clean.