Most of these are cheap or free, helping the family hopefully use the rewards more often-without hesitation of rewarding them for behaviors because it costs money...
make a cape out of an old t-shirt
make a bracelet/necklace
the idea here is to do an activity with the child, giving them some one on one positive attention for their good behavior.
mom and dad dates
See mom dates post here
break on responsibility
stay up after bed time a few minutes
get out of a chore
get help with a chore
after Halloween, there should be some treats to add to a prize box, but you can also encourage parents to take a trip to the dollar store and add some toys or activities if they don't want to reward with candy too often.
Enjoy, and happy Sunday!!