In Europe and Asia (Japan) bidets are very popular among riders (horse, bike, motorcycle) as well as with older people who suffer from hemorrhoids.

This video shows a lost cost Asian style "poor man's" installation of a bidet with an existing toilet. An easy DIY project.

If you only have 1 water outlet for the toilet, a plain T or T valve can be used to split the water line without heavy duty plumbing changes.