I got mine off of ebay and never had a problem, had them on both of my cars now for about 2 years and had no issues with the police or my MOT's and I have been followed a couple of times by marked police but they didn't pull me over or do anything. Might just depend on the area your from and how strict the police are.
My mate was pulled for *supposedly* having fog lights on but it was simply the fog lights that come on when you turn a corner and they tried to give him a fine. They even said they are pulling people over for small things since they are trying to clamp down on people meeting up in car parks and chatting. They never seem to like it when we are having a good time. Its not like we are doing anything wrong either if we are sitting in our cars chatting to each other and not out raping women, burning schools down or drinking in a playgorunds
Run my pressed metal plates since jan i travel the country often being followed by marked units, hitting anpr traps, been stopped at a vosa checkpoint with them on no problems at all! Just got a warning for one tyre being close to limit