You might want to add the Jing'an Hotel and the Shanghai Hotel to your list as fall back options. They are both behind the Hilton, and for I can tell, they might actually be owned by the same company. But, once get below y600 per night in that area, beware that hotels tend to have nice rooms and dreadful rooms (dark, pint sized, self contained plastic bathroom... airplane style).

Let us know what kind of rates you're getting across the board, and we'll opine accordingly because prices fluctuate a great deal (i.e. during the first year the Swiss was open, it was possible to reliably get rooms there for y350 per night!, and I've seen the Puli as high as y5500, and as low as y1800... which, is still $300, but it is a very nice hotel).