Mazda Rx7 Antifreeze problem?

Alright, so my cousin is going to sell me a late 80s model rx7. 5 speed turbo for 500 bucks. He said it burns a little antifreeze. What does this mean exactly. What exactly is the cause of this. I drive 350 miles round trip a weekend from college to home, so i need a car instead of my old chevy. How long will this car last me. It is currently running fine. I'm just worried about the antifreeze problem. Hoping its not the apex seals.