craftgrrl | birthday favor crafts??

My son's birthday is coming up and loot bags cost so much these days, I like to plan crafts for the kids where they can take what they made home as a party favor and have an activitie to keep them busy at the same time. A few years back I bought a box of light switch plates for the kids to paint and take home. I also got some plastic green potting plants and soil from my mom's and a few packages of flower seeds from the dollar store so the kids could pick and plant their own flowers and take them home to care for. Now my son is turning nine and I'm having troubles thinking of some good cheap ideas that would even interest kids their age. I'm thinking maybe painting shirts or pillow cases but even that could get pricey depending on how many kids he wants to invite. Please help!!

ETA: looking for crafts that you end up with something worth keeping, not the kind of craft that ends in the trash by the end of the week.