Based on your budget I give you the following advice.
1: do the car to Shanghai (50 ~ 60 / person) and then buy a map of Shanghai (3 yuan or so) the whole tour all do bus (2 yuan / person / time, do a few times by your tour line decision, but certainly can not be called a taxi)
2: accommodation in general, small hotels (the more remote point of the city center of the price of the very expensive) 70 ~ 60 yuan / person / day, according to the 4-day 60 yuan calculation is 480 yuan. The price is very expensive, 70 to 60 yuan / person / day, according to the 4 days of 60 yuan is 480 yuan, there is a kind of rental beds, but I do not recommend you, because it is a lot of people living in a large room, more chaotic (if you have friends and relatives in Shanghai, and what the lodging costs can be left)
3: meals, the general standard of dining in Shanghai is about 10 yuan a person, 4 days, 2 people is 80 yuan (can not order only eat a set menu)
4: attractions, Nanjing Road Pedestrian Street, Huaihai Road, the Bund, the Bund, the old temple, the Oriental Pearl Tower (tickets 80 yuan / person) Jinmao Tower (to the 88th floor of the sightseeing 80 yuan / person) Pujiang River tour (25 yuan / person) Shanghai is based on shopping (shopping costs do not count). In Shanghai around there are some attractions such as Zhouzhuang, Sheshan what is not recommended to go.
I roughly calculated that just the above I counted on more than 500.
If you have a place to stay in Shanghai, you can play for a few more days (accommodation and meals account for most of the cost), if not, it is recommended that 1 to 2 days maximum.