[v8volvo]

Hold out for a 7 series, they are better in every way except that some prefer the styling of the 240s. 700s are much less prone to rust, they handle better, more room in the interior, and a lot of little stuff on them is better designed and tends to last longer than on the 200s (seats, wiring, door handles, etc). The only real common issues with the 700s are that the headliners eventually fall down, and some of the front control arm bushings tend to wear out prematurely (costs $20 and 30 minutes of work to replace). Other than that, they are about as bulletproof as any car ever made.

If you want to check the 240 out for rust, the key places to look are the "butt cheeks" (the areas right behind the rear wheels where there is a sort of depression for holding the spare tire in the trunk, on both sides) and the floor right behind the driver's and passenger's seats. 700s eventually rust underneath too, but have much better materials and rustproofing than 240s so it takes a lot longer for one to get really bad.

200 and 700 series Volvos are both great cars, you can't really go wrong with either one... but if you already prefer the styling of the 700 series, I would wait for one of them to turn up since they have the above advantages plus the TD engine, which is a big improvement versus the NA motor.