Japan's robo-toilets are legendary, and indeed models like the Toto Washlet offer top-quality anus-hosing action. (Although their real strength is the hot air drier.) But importing one costs at least $500 — more if you want the hot air flap chapper — and they're unsightly, ruining the simple lines of a toilet and making it feel like you're taking a dump in a refrigerator.
Consider instead the "GoBidet", an elegantly simple chrome unit that fastens to the side of your existing toilet. A small handle moves its spigot into place — "In the pipe, five-by-five" — while another turns on the water. (This water should be warm if you want to experience all a bidet has to offer.)
You'll forgo the hot air drier, but your bathroom won't look like an appliance store, either. Best of all, it's available for just $115 from many suppliers.
The below video shows the GoBidet in action (sans user) as well as basic installation.