Paint on my SD

The paint on the trunk lid of my 300SD is starting to lighten and the gloss is starting to chip. The area affected is only on the trunk lid and rest of the car is in pristine condition.. i have also noticed that the paint is only chiping on top of the metal beams that are under the lid.. that form the triangle?.. any way i wanted to get this painted and i asked my local Earl Schw. how much it would cost me.. he quoted 75 if he used his own paint but it may not match.. So i was wondering if it is possible to order paint from somwhere and give it to them to use it on my car ? is this possible?.. if so how much paint would i need for the trunk and where could i get it from? .. the color is a Matalic grey ish light brown.. color..
thx - Jivesh