Our butcher friend gives us heaps of marinated stuff, in all sorts of flavours, from red Thai to BBQ. One I like to make on chicken wings (but did try it on chicken breast the other night- cut breast into three even size pieces, marinate for at least three hours, and cook very slow- turned out very tender), is a combination of barbeque sauce, oyster sauce, sweet soy (kecap manis), and Worcestershire sauce. Not sure of the quantities either, but slightly more barbeque sauce than the others I think.
Occaisionally we will buy marinades, but more often than not we will have our butcher's stuff (which is also homemade) or our own homemade.