3000 RMB is enough for 3 days not including hotels. 1000-1500 is good for 3 days, not including shopping or expensive bars or restaurants.
It can covers the overall expense but for high standard of accommodation, 3000 RMB may be not enough in Shanghai.
3000 RMB spending money for 3 days is ok if you stick to beer and basic spirits. If you plan to have decent wine, your budget will be rather limited for 3 nights out.
And if your budget shall includes shopping, hmm not good at all.
Foreingers can stay 6 days visa-free in Shanghai, Jiangsu, Zhejiang very soon.
a commen buget per day in Shanghai:
250-350 rmb for basic clean hotel.
20 rmb for breakfast
20(simple fast)-200(hearty) rmb for lunch or dinner.
sightseeing spots: Beware, this can a major cost, unless you are not interested.
Agreed re: sightseeing spots. The pearl tower and the swfc are both 150rmb for the basic ticket or there abouts. The jinmao is pricey and the the new tower (shanghai tower??) is not yet open for sight seeing. The puxi side of the bund is pretty non descript imo but that is the side you should be on when the buildingd on the pudong side put their lights on. Thinking its about 5:30pm at the moment