This is definitely a more advanced project, but with less than $75 in parts, you can build your very own working Acoustic Tractor Beam:
You’ll need to 3D print some parts, and code your own Arduino, and check things with an oscilloscope, but if you’re looking for a fun project that ends with the ultimate desk toy, this is it!
For complete instructions on how to create your very own Acoustic Tractor Beam, check out this Instructables.