Shanghai is a real shoppers paradise, with plenty of places to splash the cash, from glitzy malls and department stores, to the madness of Nanjing Dong Lu, where hundreds of shops stretch into the distance. Yunnan night market is a good place to pick up some souvenirs or locally produced handicrafts - as well as every pirate film you can imagine.
Bargaining is acceptable in all shops, although unless your Chinese is good, you won't get much off. Antiques over 100 years old require an export license to be taken out of the country.