Used Engine purchase

Bought a used engine from him and now he is refusing core. I called about pricing and he gave me an exporbiant price,said no thanks but everyone else is half and i'd rather drive another hour to pay half the price. Get a call back a few minutes later from him asking which engine it was again? Oh,you wanted that engine,well i've got it for $450. (Down from$900) Showed up to purchase,and then he said no warranty for that price-I said no thanks and he said okay 30day warranty. So price was $500 (450+50 core) and tax of $49.xx. Trying to return the core and he said there was no core charge. He showed me on the reciept where it showed engine $500 and tax and that was it. Well I got news for him,He was so shady in the first dealing that I recorded everything he did with motor. I also recorded the warranty promise since I had to force him to write it on reciept and knew he was shady. Also,he gave me the wrong engine. Said the toyota engine would work instead of Geo,and he's right. However,since it did not have the correct stuff for my application (cause it was incorrect engine) the entire engine had to be disassembled all the way down to the oil pump and rebuilt with the correct geo parts. Just stay away from this guy,i'm a professional tech with alot of years dealership experience and currently have my own shop doing custom engine swaps,electrical harnesses and other hot rod work. I wouldn't borrow duct tape from this guy if I was stuck in the desert and had a blown hose-I would walk to someone I could trust first.