At $5000, make sure it is a clean title. You'll probably have the typical F-Body issues: cracked dash, dead window motors, whining rear end, etc.

I would have a mechanic check it over carefully. When I was searching for my 1998 Z28, I looked at some in that range and just as @toyotagrl said, they were ROUGH. 

I wound up buying one for $2000 with a blown motor, BUT my case is unique as I already had a replacement motor ready to go and access to all the parts to make it roadworthy as it is what I do for a living. Most good, road going Z28's are over the $10k mark.

Bottom line: ask the seller if they will let your independent mechanic look at it prior to purchase. You may get a "no" immediately, in which case walk. If they are ok with it, definitely have it checked out. Realize it is now a 23-year-old car. I love mine...but I'm also quick to say I've worked on every single piece of it and replaced most as a lot of things simply failed due to time. If you want it as a toy, you could be ok but the other advice I have is do not buy it as a daily driver. It doesn't have the reliability for that at this point.

Is it a Auto or manual 6spd? Creampuffs go for much more $$. At that price, don't be surprised that it's been driven hard and worn out and beat up. 7 years ago, I was looking for either a Z28 Camaro or Trans-Am, and I walked away from all the ones that were in the $5-8k.