Dartin for Divorce

So right before I bought my AVS2 carb I found one local, the guy never got back to me. Well today he got back to me saying he would take 200 for his... I think I am going to buy it, then go return the one I paid full price for. Essentially getting back 150 bucks; does this make me a bad person? haha.
will they take it back if it's been installed?