More details? Year? Miles?
Things that would turn me off when looking at an SVO:
-Rust. I'm from up north, don't want a rusty car ever again. If you see some, there will be more where you can't see it. Check the frame rails just ahead of the firewall. There was a red 86 I looked at a while ago up there that looked NICE on the outside. I was really psyched...till I saw the framerails. Shameless plug...I have a bunch of spare body parts should you need 'em...
-Torn bolsters on the driver's seat. I hate that because they make the interior look like crap, and there's really no easy way to fix it (swapping seats is easy, but finding SVO seats to swap...not as easy).
-Ripped up leather parts - shifter knob and steering wheel, mainly. Just look crappy. You can get a rubber GT wheel hoop and put the SVO center in it. Kinda ghetto, yeah, but good for a driver. Horn may need some rigging to make it work.
-Yellowed headlights. The passenger side outter marker is 'quite' expensive to replace, if you can find one. The rest are easier to find, and 'just' expensive.
-Those f'n upper wings...they look cool as hell when they're in great shape. PITA to fix - I only know one person who can do it worth a damn.
- Cracked header panels. The fiberglass behind the bumper cover. If the thing was in a light front-ender, it's pretty common to have the skin replaced, or not torn, and a cracked header panel. I think you can get a repro unit still, but it's $350 I think. It may not even bother you, but still something to look for.
-Any missing SVO parts, mostly the stuff on the outside. Like Dave said, that stuff is expensive. In fact, it kinda turned me off on SVOs altogether. Spats can be pricey, sail panels aren't too bad, door bumper trim will surprise you! $$$
-For some reason, I remember the E-brake cable being a PITA to replace if needed, so if that's important to have working, be sure to check it.
As for motor stuff, I wouldn't worry about a thing. That shit is ALL cheap. If the turbo is bad, try to get him to knock a bunch of money off the price, but don't let that keep you from getting the car. The center section is common between a bunch of other 2.3t cars, and that's all you'd need to replace (we just did one Sunday, as a matter of fact, and got the center section for free).
Same with trannys - regular 4-banger trannys work just fine, as long as they're 87 and up (Levi...?).
If the car smokes, especially on startup, my money is on it having the wrong PCV valve and/or bad valve stem seals. If there's oil on the intake side, all around the vicinity of the #4 injector, again I'd point at the PCV valve.
If when driving it, the thing is sluggish at first, then starts pulling good, then falls on it's face, they were probably messing with the boost and turned it up a bit too much.
Early cars had more bugs than later cars, from what I've seen. If it's an 84, make sure the fan kicks on when it gets hot. Early cars seemed more likely to have oil everywhere, since the PCV setup was a little different.
There's probably more, but I put all this stuff in here in case you run into a basket case. They're old now, and a LOT of them are like that at this point. And most people don't even know how to fix them, so you tend to find all kinds of whacked out crap on them by now. Even if the car LOOKS good and is truly solid, I wouldn't be suprised if there's something not right with the motor - TPS calibration, boost leak, high idle, oil leak, stumble/hesitation - use that to talk him down.
If I was looking for an SVO, I'd look for a straight body with good paint and interior. Everything else is cake. I wouldn't care if it even ran.
If you want to put my number in your phone, PM me and I'll send it to you so you can call me when your looking at it.