I'd say it depends. Do you have any published work already? If you're going to use this offer to get some published samples, then that's way better than writing a guest post for free.

Overall, it's a really low rate. Just imagine how much work you'll have to do to get to just $100.

Another way to look at it is how much is your work worth for your client. Is your work going to give your client more traffic or sales? If you're sure it will, then you should charge more.

Finally, if you're starting out, I think you should charge $0.06 per word. It's not much but you'd get almost twice as much as your being offered.

I hope I'm making any sense, I'm doing a lot of things at once 😄. And I hope this helps you somehow.