BMW town (
www.bmwtown.com) has the E36 M3 front spoiler and splitters for $100.
RGM Styling (
www.rgmstyling.com) has the same front DTM splitter (FS 103 E36), it may be cheaper. They also have just the side splitters.
Rieger UK (riegeruk.com) has some splitters like that, that will atatch straight to the bottom of the stock bumper.