How can I send text messages anonymously?

I don't want them traced back to me.

What's the best way to do it for small batches?(at most 100 texts a day).

So far the best I've found is to just get a sim card...but I'm sure there has to be a better way

There's a ton of free texting services that you could use. They'll give you your own phone number for the texts and everything, and you don't need to use any sort of real info to sign up either. There'd be almost zero way to trace it back to you.