Shanghai Shokudou in Ebisu, just east of the station, is a somewhat new and fairly plain Chinese restaurant that has large amounts of decent food at relatively low prices (for Ebisu). I usually get the large chahan (almost big enough for 2 people) plus a plate of 8 large sui gyoza, all for 950 yen. The interior is basically like a cafeteria, but I doubt anyone goes there for the atmosphere. The Ebisu branch (I think there is one in Shibuya too) has three floors (B1, 1 and 2). Service is quick one day and slow the next. If you are in Ebisu and want cheap Chinese then this place and Chinese Cafe 8 are good options, portions are slightly bigger here but CC8 has a larger selection.
basic information in Japanese
some more pictures
Diddlefinger Map (English labels)