Generally when things seem too good to be true, they are. That said, I didn't see anything negative. It just doesn't make any sense unless there are a ton of hidden charges. I'm curious to see what kind of responses you get.
Amended: It's sort of weird, but I don't see anything bad about it. The agency, Appalacian is BBB approved. You might want to check the individual hotels out on trip advisor, the $189 place looks a tad sketchy. I just don't see how they can charge only $189. But then people on spring break tend to be willing to put up with a lot.