Dixie cups also work for treat toys! Similar to the toilet paper tube, just insert treats and crumple it up. My girls also like to just have some dixie cups lying around the cage, for shredding.
Also, you can use popsicle sticks for a cheap wood toy, to toss in the cage. Many people buy their rats craft sticks from the dollar store. If you're not certain about the safety of them, you can buy food-safe popsicle sticks meant for making actual popsicles with! I've only found them online, though. A lot of people don't realize that "craft sticks" aren't necessarily safe, unless they specify that you can use them for making food items. I still buy the rats some "craft sticks" every now and then, but I do worry.
I also buy them paper straws and cupcake liners. Rats love shredding / nesting, and my girls will chew them up overnight. They are both meant for eating off of, i.e. human consumption, so they are safe. Some paper / cardboard has weird glues in it. I know the glues probably won't hurt a rat but I am over protective with my rats' toys!
Also, bird toys can be a big hit. Or not. My rats have always been "meh" about hard, wooden toys. They prefer softer (but safe) toys, like yucca bird toys.
Lastly, here's a chinchilla etsy shop that I love:
https://www.etsy.com/shop/TaylorMadeChinchilla
I spend too much time thinking of rat toys... you can tell!
