Please provide your requested size, quantity, artwork, material and process, we’ll provide unit price and set up fee for your reference.  The more details you offer, the more accurate price shall be provided.
Die casting is a metal casting process that is characterized by forcing molten metal under high pressure into a mold cavity. Once the mold cavity is filled, the pressure is maintained until the casting solidifies after cooling down. Then the half-finished products would be polished, electroplated and color-filled.
We’ll prepare film which has your design already and then transfer your design from film onto a sheet of brass. Your design would be etched by acid chemical, and then we’ll have the brass with electroplating and color-filling.
Offset printing is also named 4 color process printing (Cyan / Magenta/ Yellow & K-Black), no matter how many colors involved in the art, we charge the printing set up fee for 4 colors if there is no metal border left on the edge or 5 colors if metal border is necessary on the edge, the extra one is for white background color.  Generally speaking, if the pins must be made by offset printing, there should be no PMS numbers instruction because we will use CMYK to present the colors.  Offset printed lapel pins are perfect for designs that contain gradient colors.  We’ll print your motif on the metal and then die cut each piece.
Imitation hard enamel is invented in early 1990 and also named Soft cloisonne or synthetic cloisonne. 
It would be filled into the stamped metal first, and have polishing and electroplating afterwards. It is hard to tell the difference between real hard enamel and imitation hard enamel colors, but if you stab the color parts with knife point, imitation hard enamel colors will get visible marks, however real hard enamel colors won't because colors are as hard as tiles. 
You could choose offset printing for your design.