I have to say they look pretty good.
A quick Google shows that they're probably made for the German market.
http://www.fahrrad-online-shop.com/mainstream-classic-plus-2009-p-13882.html
(doesn't seem to be an English translation but you could try putting it through google translations - it looks like that's where the text on the
probikekit site has come from!).
The only major questions I'd have is about whether they are waterproof, although the blurb on the probikekit site suggests they are, and about how good the rack fixings are. They look OK but it's difficult to tell from the pictures, and ultimately what matters is how well they work.
I'd say they were worth a punt, if when you get them you're not happy you could return them to probikekit (providing you do it within two weeks and they're still in saleable condition etc).