We've had one of these for a couple of years now:
American Standard 5900A05G.020 Aqua Wash Non-Electric Bidet Seat
They're only around $70, and are quite easy to install—you simply attach the seat, then insert its connector between your toilet's water supply and hose. The controls are very subtle, just a couple of small chrome knobs at the rear side.
But it works beautifully. When you turn it on, the little spout extends into just the right position, then retracts when you're done.
I can't say enough good things about it. (Well, people don't usually want to hear a lot of details about your bidet seat, LOL—this is my first opportunity.)
The only special consideration is that, because the spout mechanism requires some space at the back, the part of the seat you sit on is somewhat smaller than usual. It just feels a bit different, though; it doesn't interfere at all with doing your business.
I give it 5 stars. I feel sorry for all the peeps going around with unwashed fannies, too—it's so easy and cheap not to.
Good luck!