Traveling from Oaxaca to Huatulco (Mexico City)

Hello Friends,

I am planning a trip to Mexico end of May and wanted to also visit Huatulco as well. Do you know what is the most cost effective and safe way to travel there? between bus and flying? I'm seeing the prices for plane tickets at $450 which a lot, but cannot find recent reviews about travel via bus: how safe is the ride, how good the roads are, what is the best bus company to use, etc...
I would really appreciate any help and recommendations you would provide.
Gracias

Christiane