Put your self in to sellers position... if you would be selling digitisers for lets say £5 you still would be paying at least £2 for postage. And when you selling lcd with digitiser together you still will be paying same £2 postage. Then you could look as well from other point of view... if you are manufacturing only digitisers, then you will be trying to do best quality you can get. Obviously thats expesier because of labour hrs has been spent on it. And last point of view is when you don't care about quality but do care about quantity as long it meets requirements. So you spend less money on labour hrs for testing and making clients to think that thats standart replacement because it's everywhere.
That's just my opinion though
