Shiny is a rare product (Gen,producer,gun,wall,etc...) That it has a chance to you spawn by buying any!
(Shiny colors are not like non-shiny)
The chance to get a shiny is hard to tell but the more REBRITHS you have the higher chance to get one.
The shiny sells for x10 more then the normal one, but its NOT any better. its just more rare.
YAY it worked ! (actualy i never get one but cool info !)