I utilize common local store items the most. Whenever I get a coffee out, I ask them for an extra cup. No one has ever even questioned it, let alone said no. Going to a fast food restaurant? grab extra straws, paper ketchup cups, I've even asked for extra clean french fry boxes, or chicken nugget boxes.
Dollar store- baby toys, or measuring cups/ spoons. And lots and lots and lots of the crinkle shredded paper and muffin papers. They would also have paper plates, and paper lunch sacks.
Paper 5oz dixie cups (not the waxed ones, the plain paper ones)
if you have a scroll saw or band saw - plain pine boards from home depot/ lowes. They even have SS quick links at lowes.
Pine cones. This past fall my kids and I spent over an hour walking around the local mall. All of the pine trees in their landscaping are the good woody kind. We just make sure not to grab the ones with pine tar on them, and bake them in the oven.
You can get sisal and jute from hobby lobby. I also get popsicle sticks, and mini vine wreaths there.
The biggest items that I buy online are munchy vine balls, and finger traps. I like to check Windy City Parrot for stuff before I look elsewhere. I have always had stellar customer service there, and they have free shipping over $49, (easy peasy!) or $6 flat rate for anything less. I just get a bag or two of food, and I'm easily over the free shipping limit. I generally need to order our food online anyway, why not get free shipping!
I also have amazon prime, and sometimes, although rarely, you can find some good deals there, and shipping would be free if you or a loved one has prime.