I have seen many models in many shops on lamington Road.
Since i was never interested in purchasing it never enquired about it.
generally the case comes with m/b + psu. (200 ~240 watts)
m/b's includes the complete spectrum of both intel and amd cpu's.
The cpu + hd + optical drive +rams you have to buy seperately or use your existing ones.
The m/b generally comes with built-in graphics , and some do have 1 agp slot for using a "Real" graphic card. + 1pci slot for other expabsion cards.
Shuttle , Aopen , IWill , Biostar are some of the popular co's manufacturing it. (on the lamington road you may find many more chinese made brands)
The price should vary from 8 to 15 K depending upon the m/b and the brands.
best would be if you actually do some legwork and go window shopping leisurely.