There aren't enough shops in the old town but yet, fortunatly not too many.Some of them sell outdoor clothes, some animals leather products(awfully), some tibetan handicrafts.
What to buy: The only thing that really caught my attention was the tibetan pendant, there were so many and all with different colours, that's the only thing I'd buy here.
What to pay: You can get one pendant for less than 10 dollars.
Because at 5000 meters above sea level, you'll find your lungs very hard to breath and the weather is extremely different, so I guess that's a warning. There not much to shop in Zhongdian, just a few rolls of shops but very welcoming owners.