my overall impression of stuff from Planet-X is that if you get a cheap thing from them it will be rubbish and not worth the small amount of money it cost
The things I've had from PlanetX that have been good value are basically:
Merino socks, which are excellent
Merino baselayers with a mesh back (ideal for recumbents) that they no longer do
Disposably cheap battery lights (for emergency backup purposes and giving to people in need of lights)
Occasional deals on unpopular tyres (studs in summer, for example)
Occasional deals on chains
Particularly disappointing have been:
Merino arm warmers (weird size, crap elastic)
Overshoes (eaten in a single ride)
Somewhere in the middle:
Smart-clone lights (obviously low build quality, but work fine for about-town use and I don't have to worry about them breaking or getting nicked)