This is by far the best market I know of.  It's huge and has a facinating collection of parts, tools and supplies.  I did two visits out here on this trip, once by bike, once by bus - I prefered the bike.  The bus stops are both decent walks at either end.  I took the e33 express bus which seemed to puzzle the driver as the cost is fixed (10RMB), not cheap and I only travelled two stops.  I've included both the bus and bike maps below.

Since I first visited this market the car park has been sold to residential development and it's surrounded by apartments towers.  It's not hard to imagine this market moving further out a some point.  The photo shows the main building and a smaller supplies building.  The supplies building is also worth a visit for stuff like packing, anti-static apparel etc.  The first and second floors of the main building are enormous and loaded with great things to see.  The third floor is PCs and pos terminals, worth a quick look.  You can see the scale of the place in the photos of the maps, each small booth is about 6'x12'.