Couldn't agree more with Jonathan and 38th..........but then as a repairman I have a vested interest :D
Had a guy bring a Jackson to me last week to which he'd fitted a new locking nut, obtained direct from Floyd Rose in the US. Only problem was it as a Korean Jackson, and the new nut lifted the strings about a quarter inch above the fretboard!! People buying the wrong thing is much more common than you might believe.
Don' t forget also, that we in the business have a good idea where to obtain stuff at good prices, and if that means the US, that's where we buy from. I get Fender parts from the US, and buying in sufficient quantity to negate the problems with minimum shipping costs, can sell them here cheaper than Fender's retail. For non genuine stuff I usually use Allparts UK (was Pincotts) and WD Music Products, both of whom give a very good service and there are others equally as helpful.