If your looking for a cheap foraging option that can be bought locally, a shallow tray filled with crinkle paper or dry grass hay makes for an excellent basic foraging toy. Keeps them entertained for a long while and it's reusable.
I bought these large saucers from the garden section of a home improvement store. They are used to catch water under large flower pots. But any appropriately sized tray or shallow box would work. You probably already own something that would work. I buy hay for small animals from the pet store. A small bag should last you a while. Or you could use somethimg else, like shredded paper. I toss in a generous handful of grass hay, then sprinkle a variety of goodies on the grass for my birds to find. I usually add a variety of seeds, nutriberries, edible flower petals, dried herbs, freeze-dried chop, calcium clay, and other natural treats. To make it a bit of a challenge, I give the tray a little shake, so most of the treasures fall to the bottom and are hidden from view. But the birds know to start searching as soon as I bring out a fresh tray. And I will occassionally refresh the trays with more treats, so they keep coming back to check again.
It is a fun game ... and a nice place to take a nap.
I haven't used these indoors, but I recommend putting it on hard floor, so you can easily sweep up any grass or paper that escapes the tray. Or put a small foraging tray inside a larger tray to catch any mess.
Another simple DIY foraging toy just uses little paper cups. Start by offering the treat cups open and accessible, so your bird learns to recognize them and knows there is good stuff inside.
Then gradually increase the difficulty, by folding or pinching the cup closed. See how long it takes for him to work out how to reach the hiddsn treats!
Where I live, these cups are called "soufle cups" or condiment cups. You can buy them in packs of 50 or 100, so one bag of cups will last a long time and offer a lot of destructive parrot fun.