I agree with Greg here, postal money orders are backed by the federal govt and the postal service takes an unkindly view of people who abuse that system! This clown is using the new tried and true method of Instagram that scammers now prefer! If it were a postal money order, I do believe you would have some pull with the Feds to help straighten this out! Paypal does not always have your back, as a matter of fact Ive heard many people say that Paypal doesnt have your back at all!!
I also agree that I would be over kicking my brothers butt if he ever tried to scam anyone by using a money order to rip them off, but I don't have to worry about that because he is as honest and trustworthy as I am, which may not be a good analogy!!!
Sorry to say, but the OP here ignored some major roadblocks in this deal! Never post a wanted ad, that seems to be the first way a scammer with low/zero posts can link on to you....never send money by Instagram, especially to a low/zero poster....never deal with anyone on the web that doesn't have a reputation amongst the peers of the site you are dealing with...and always send any money by a secured method!! Even then there is a chance you'll get scammed...think Ply30!!!
Sorry the OP got scammed, but the parts are not worth the risk!! Geof