The Google Home Mini is about 50 dollars and is a really cool and popular gadget. Other cool gadgets are Bluetooth wireless speakers, which you can find relatively inexpensively. These speakers are cool because you can get great sound by playing music from your phone- no expensive system required!
More low tech but cool gadgets include carved wood iPhone cases, and a ring video doorbell which allows you to see who is at your door. You can also find some cheap gaming gadgets that are impressive.