Go to the pet shop and select the dragon. It will cost about 850 gold. Change the color to all white. It will now cost exactly 340 gold. Buy the white dragon. Go to the paint shop next door. Paint your dragon a different color for between 240 and 320 gold.
Go to the pet store and get the dragon. Then, change both colors to brown. The price will now be 288 gold. You can go next door after you buy the dragon and change the color at the dyers.