Def of OEM:-
"An original equipment manufacturer, or OEM is typically a company that uses a component made by a second company in its own product, or sells the product of the second company under its own brand. The specific meaning of the term varies in different contexts."
"OEM's are the industry's brand name auto manufacturers, such as General Motors, Ford, Toyota, Volkswagen, etc. The OEM definition in the automobile industry constitutes a federally-licensed entity required to warrant and/or guarantee their products, unlike "aftermarket" which is not legally bound to a government-dictated level of liability."
If you do a search I'm sure that TT found out what the cost of the OEM tinted glass was, as someone has asked this question once before.