Oh don't worry, this is simple.

Reply to him and copy exactly what it says in the auction. Shipping Cost US $35.00

Then simply say: Your auction says $35 for shipping. According to Ebays terms, I'm not required to pay any more than that. If you feel you made an error on your auction, you can contact ebay and work it out with them. As it stands right now, the auction was for $35 for shipping and that's what I'm paying. Please keep in mind that an ebay auction is a legally binding contract that will hold up in court.

See, you are simply saying, bish no. But it's nice and too the point without being too rough. Do not pay him the money, it's a scam way to get more money out of you. Don't fall for it.

If he continues to insist on paying, don't even bother with replying to him again. It's just a stupid waste of time, just report him to ebay and be done with it.