Hello there , this price for just channel.
I'm expert of whatsapp and I have my own API and working official system . Technically not blocking from whatsapp . On the net maybe you can find "Whatsapp PHP Api" but it's working maybe few hours then banned from whatsapp.
You can check my reviews , I can code for you best program and you can use this sending system. You can add your own channel and all operations . Details over chat.
Have a nice day !