"My Craigslist seller listed his hitch in January, and has not replied to email, text, or voice mail. "

Okay from your original post it sounds like you have been waiting since January ? Sorry that I read into this wrong. Now that you mention that you sent him a inquiry on Friday and have not heard from him well just wait and see. It being over 30 days since the initial listing and you have not gotten a response over the weekend, chances are its no longer available. Anyway he has got your inquiry and will choose to respond to you one way or another.