Seems to me a lot of them are Autobahn88 kits, and I've seen them sold for a lot more than the £250 you can pick them up for off eBay.
I've had one myself, and the kit seems just fine. However - it'll need a bit of modification to your precious; wiper fluid bottle and battery will normally have to be relocated to the rear of the car. I also noticed that the piping that was supposed to go over the hose from the radiator didn't do just that - go over that is. So - the radiator would have to be lowered about an inch, or you'd have to come up with some custom piping/hoses.
However - once mounted, they should be quite good. I went for an ARC TMIC instead when I saw what I had to do to fit it. Ironically, I'm considering getting an FMIC again.