TX resident filing small claims suit in Michigan?

Assuming that the travel agent does not simply agree to pay you when you serve him with a complaint, you would certainly have to appear in Michigan to litigate any claim against him.  If this would be inconvenient or too expensive for you, you hould consider filing suit in Texas.  Although most small claims court have limited jurisdiction, it is likely that a Texas civil court of general jurisdiciton would likely have jurisdiction over the travel agent if he/she/it has "minimal contacts" with Texas.  Even without knowing if the agent provides any travel services in Texas (i.e. arranges trips through Texas) it seems from your email that the agent dealt with you in Texas regarding the contract that is now in dispute, probably advertised in Texas and/or solicited your business in Texas.  Thus, it is likely that the Court will find "minimum contacts."  The downside is that small claims cases are generally much cheaper to file and prosecute, and may move faster.