I was hired on short notice by a company as a consultant to assist with the purchasing of steel to expand an existing company . I was unemployed and prior to accepting the request I asked what the terms were and I was informed that all travel expenses and accommodation would be paid for and I would be paid a fee of $140.00 per Diem to accompany the company owner to china to purchase steel as he had no prior knowledge of steel quality and steel grades and as I have this knowledge and came recommended to him he asked me to assist him under the conditions mentioned above once we arrived in china I was informed that he was only prepared to pay me once we returned back in the U.S.A and now 5 months later after numerous requests for my money the owner is now telling me that we had no such agreement and he was having trouble selling the steel so therefore he can't pay me what choices do I have to collect my payment of $2240.00 which he owes me

You sue them in court, you can use small claims court since it is a small amount of money.

You didn't get this in writing? That wasn't very smart of you. I assume you can prove that you did make the trip with him. That should give you some case to sue him over. But that's your only option.