Where online can I purchase a vehicle tracking system that be detected?

It's not clear what you mean by "be detected." Do you mean a tracking system that can be easily detected by others, or a tracking system that is difficult to detect? If you are looking for a tracking system that can be easily detected, you can try searching for "fake GPS trackers" or "dummy GPS trackers" on websites like Amazon or AliExpress. If you are looking for a tracking system that is difficult to detect, you may want to consider hiring a professional or researching options that are designed for covert tracking.