"No new car really completely keeps its value, cars are one of the worst investments that can be made. BMW's likely retain their value better than other brands due to the companiy's high brand perception"
Deals on BMW Z3s can be found in many places, depending on where one lives. An individual can check their local dealership, which often sells used models in addition to new ones. One can also check the classifieds section of the newspaper, or sites like Craigslist.
There are many reasons the light comes on as this is a complex system. You can not turn it off. It must be reset after the fault is fixed. Sometimes dirty speed sensors in the brakes will turn it on. It could be a "broken" control module or ABS pump, both of which are big $$$ to fix. This is a common problem with the Z3s and their ABS/traction control system. If the light is on, you still have brakes, just not ABS.
It is immediately in front of the gear shift lever, just to the left of the heated seat buttons. It is the one with the arrows pointing up and down. Some Z3s had manual tops and would have no switch.