while i was looking to buy a product, a guy sent me a message stating he would sell it to me for an amount plus the cost of shipping, i agreed and gave him all of my info. he stated it would take a day to get the part, but when i didnt got the product for few days, i mailed him. he said that someone else offered him more money for it so he was backing out of our deal. can i sue him for breech of contract across state lines?

surely, you can sue him but in his state only.