I let a "buddy" borrow my 91 S10 Blazer for a couple months since he didn't have a vehicle. Well when he brought it back to me the other day, on a trailer, he said that he had taken care of it and whatnot. Come to find out he had decided to change the oil but forgot to put new oil back in. So now my engine is dead! My neighbor told me that he has a fuel injected 4.3L with 150,XXX miles that I could buy from him. My question is how much should I pay for it?

 

With a 150K on that motor, I wouldn't offer more then $200 if it's already pulled.
If it's still in the truck, $100.

With that kinda mileage I would atleast pop the oil pan and take a look at it, I would most likely pull the intake and heads also, atleast you'll know more about it and it's also easier to install head gaskets, etc while it's on a stand rather than in a truck.

How bad is the motor you have now?
If it didn't sling a rod, might be better off just having yours machined and do a simple rebuild..

Good luck.