When we installed our first clients over a year ago we oversized the trans by about 350w to enable them to expand within reason. we did 1 expansion of 8 lights... then another of 4 lights. Thier 900w CAST trans is now comfortably full. They just called wanting to expand again (not sure how many lights but if its more than 2 or 3 we need new trans). I wanna go in prepared. Do most of you guys take trade ins and give credits on the transformers ? If so how much ?