I am looking at buying a 1996 mitsubishi eclipse. The guys tells me that it needs rod bearings. It runs but knocks. I read somewhere that the mitsubishis had problems with the lifters that made them knock. If this is all that is wrong with it I may buy it but if it is more involved (engine tear down and rebuild) then I am going to pass. Is there an easy way to tell?

No.

You don't mention a price nor the number of miles, but I've just got to ask is: If that engine is making noise and the seller is telling you that it's rod bearings, why not consider a replacement engine that isn't making noise?
What's the cost of the replacement plus the cost of the car, are you ready to pay that much?
ie: short block = $4600 +/-, then the labor...
You see?
You may want to keep shopping.