Maybe I'm just anal, but I wouldn't buy a car of that age with any more than 100-120,000k's on it. Resale values, plus age of components I wouldn't bother. I was in a similar situation when I bought my SSV, looked at a few around the 80-100K range, one had been looked after the other two hadn't, and it was very obvious apart from the odometer reading. The one that had been looked after was pretty good but wouldn't take lower than $26K (I was only looking for an SSV, wouldn't consider an SS). Ended up finding mine with only 35,000K's (its a late 2006), for that price from a dealership. Lucky I did too because it needed the balancer and sump gasket done under (used car) warranty.
Common things to look for on V8's, especially if an early build date - wobbly balancer, squeaking belts when cold (especially AC belt), leaking sump gasket, lifter noise. Some have problems with the AC belt (and then main belt) being thrown off the tensioner, especially when driven hard, there was a revised AC bracket assembly with a second pulley released in 08 from memory. Might be something to look for too.
Having said all that, if you can't wait for the right car for the right price, I say take the plunge and do it.