Good luck with that if the seller did not sign and enter into a contract with you.
That's a tough situation, and you may a have a fine case. Depending on which contract form you used, the remedies for default are probably spelled out in detail. You may also have a claim for lost Tax Credit if that applies to your situation. REALTORS can't practice law without a license, so we can only provide general information. You will probably need a lawyer who is willing to sue in Federal court (since the plaintiff will be a foreign national).
Claims where acting in bad faith is involved are really interesting in Texas, because of the Texas Deceptive Trade Practices Act. See: http://www.texasbar.com/Content/ContentGroups/Public_Informa
That may make your case even more interesting to an attorney, because the damages are tripled. We know several good ones, if you need a reference.