I picked up a couple of ex-demo waterproof red panniers recently (don't quite match, different year's models I think) for use on the tandem, because it often seems to rain when we go out on it! They're branded Outeredge, and the newer one looks identical to the Revolution panniers posted above. In fact I'm sure it's exactly the same pannier, just with different branding. The newer one has a shoulder strap which I find very useful.
I can verify they are entirely waterproof, sturdy, and they hold 23 litres each which equates to quite a lot of shopping, kids gear, etc. The only bit I'm less impressed with is the pannier hook system, but I suppose that could be changed for something like Carradice's system (which is excellent), Rixen Kaul (like the Revolution ones) or Altura hooks which are readily avaialable.
I've seen them for as little as £26 each, though as mine were ex-demo I got them for a lot less. Perfectly serviceable as "poor man's Ortliebs".