In the Chinese pantheon the dragon is the most powerfully potent of all. You can find them, large and small, in a wide variety of shops including New Age, novelty and Eastern goods shops from a few dollars upwards. The best kind are those painted green or made from any semi-precious green stone such as jade, also those carved from wood.
It is the the main symbol of feng shui and stands for new beginnings. As a symbol of water, therefore rain, it signifies wealth and abundance. It's common even for a business to display it's name in association with images of dragons to bring them good fortune.
For auspicious luck place your dragon anywhere in or around your home (or workplace) but in your living room is best. It is especially powerful placed in the east.
For more good luck charms, lucky objects and lucky Chinese money frogs go to my lucky Squidoo lens here.