How much will it cost to replace the engine? on 2002 Saturn Vue

I am thinking about buy a vue from someone. It's a 2002 but there is a knock in the engine. I'm looking to spend around 3500 on a new car total. He is selling it for 1800. Found an engine for 500 with a 3 year warrenty. Just wondering if it will still be in my price range to have it put in. Really like the car and if I can stay under 4000 then I will definitely put the work into it and buy it.

Asked by for the 2002 Saturn Vue
1 answer 3 comments
what motor is in it and stick or auto and 2.2l or 3.0l
I'm not totally sure about all of that. I believe it is automatic but that's basically all I know.
you need the size to get a labor est.big diff in price
Ok I will find out and let you know. Thanks for the help!