I just got a used '87 Samurai this summer. I've always liked the look and almost bought a new one back in '87. The dealers here in Utah were selling $8500 Samurai's for $12,000 back in '87. That's how popular they were in Utah. After Consumer Reports killed them you could buy them for dirt cheap. The used priced just started going back up in Utah so I got one for $1000.
I'm a good mechanic but a horrible body person so I was looking for one with the least amount of rust possible. Mine has a little rust at the front fender corners, and around the fender flares but none on the floorboards and very little on the springs and mechanical components.
Look for leaks underneath the Samurai. Some oil on the back of the engine is usually from a leaky o-ring on the Distributor housing and is easily fixed. Look at the oil on the dipstick. If it's black and runny and smells like gasoline then you probably have bad rings. Look for radiator leaks. The steering has a damper that goes bad and causes the steering to wobble back and forth around 40 MPH but again that's very easy to fix.
Here's a good link for Samurai info:
http://www.off-road.com/suzuki/Just click on the Samurai link for a bunch of useful information.
I have to say that this Samurai is one of the easiest vehicles I've ever owned to work on. It's simple and it works.
Hope this helps,
Matt