I go on Amazon for mine. I'm a newbie to pyrography but here are the ones I've bought.
https://www.amazon.com/gp/product/B0018N9XZ6
https://www.amazon.com/gp/product/B000FRV8XQ
https://www.amazon.com/gp/product/B01LDWP3LY
https://www.amazon.com/Gocutouts-Wisconsin-Cutout-Unfinished-Wooden/dp/B01LDWP3UK
https://www.amazon.com/gp/product/B0085TGTAS