depends on what type of lights. downlights? designer lights? obviously downlight is a cheaper choice, bt of coz ur unit has to be w plaster ceiling

If you do plaster ceiling, you only need to install downlights (RM10 for china made downlights and RM10 to RM13 for energy saver bulb) for the ceiling, and some florescent tubes for box-up lights.  Downlights are usually placed 4 feet apart (this is wat I observed), choose the 6" (wider type) for better light dispersion. 

To enhance the overall feel, u can buy 1 or 2 nice pendant lights (price range is up to you and reflect the quality.  But if not fussy, for a quick fix, u can get some big pendants with crystals' look for RM150 + or -).   Seng Hup lights along Jalan 222 have some old ceiling lights on offer, and u can also got to puchong (near Tesco) to check out the lights there.  Wall lights also got different quality.  I saw one uplight (which look like the one I saw in the magazine) which i china made, cheap only RM50 each, but if u look closely, quality very so so the joints are not so smooth ...  but asuming nobody can look that closely, then u can buy this type instead.  I think if u want good quality, I have seen some nice ones going for RM150 or more than that.    Actually if want good quality, there is no limit cuz I saw some at few hundred ringgit one

You may visit Eglo Lights gallery along jalan gasing to check out their lights.  These are austrian design made in china, but quality very good.  They do have some more affordably priced ones (mean below RM100 to RM150), and most wall lights are fitted with on/off switch.

Just a rough guess, if u are not using expensive lights, I guess RM2,000 max is enough to pay for all the lights.

Another way to keep a budget is to fix the max price u wld pay for each light, say RM50 each.   Just stick with that u will be ok.