If you find one of those egg vending machines (IE: Winnie the Pooh Keychain, mini rubix cube, little figures etc.), I think those would be popular. Around $4 each IIRC?
Rubix cubes if bought in bulk on Amazon can come close to $4-6 each. Unfortunately the boxes of 3x3x3 are hard to come by, but some of the other rubix styles might be neat on their own.
Speed Cube Set, Aitey Cube Bundle 2x2 3x3 4x4 5x5 Pyramid Megaminx Skew Mirror Ivy Windmill Sticker Magic Cube Collection - Puzzles Cube Toys Gift for Kids and Adults Set of 10
https://www.amazon.ca/dp/B07VG645VK/...5RXMTZPP38YJFB
I think 3x3x3 individual rubix cubes are like $10-12 bucks? Bulk is cheaper, if you can find it.
Metal puzzles and brain teasers might be popular.
Puzzle Boxes, PeleusTech 6Pcs IQ Brain Teaser Set Metal Puzzle + Wooden Kong Ming Lock for Children Adults MT1142
https://www.amazon.ca/dp/B01KLZ3R0S/...5G577RCQ6VGY0H
Meao 24 Pcs Metal Wire Puzzle Logic Brain Teaser Set - Metal Ring IQ Puzzles Difficult Games - Ideal Intelligence Toys Gifts for Kids and Adults
https://www.amazon.ca/dp/B08GF82SRT/...ing=UTF8&psc=1
Sensory toys as someone else mentioned
EDsportshouse Sensory Toys Bundle-Stress Relief Fidget Hand Toys For Kids And AdultsSensory Fidget And Squeeze Widget For Relaxing Therapy-Perfect For ADHD Anxiety Autism
https://www.amazon.ca/dp/B07D1KRT47/...ing=UTF8&psc=1
Flashlights
EverBrite 6-Pack Mini 9-LED Flashlight with Lanyard, Impact Handheld Torch Assorted Colors with 3AAA Battery Included (Hurricane Supplies, Camping, Hiking, Emergency, Hunting)
https://www.amazon.ca/dp/B071SJ6NBS/...BFKZW6BF3K9FXW
3 color pen
BIC 4-Color Shine Ballpoint Pen, Purple Barrel, Medium Point (1.0mm), Assorted Inks, 3-Count
https://www.amazon.ca/dp/B07FCVFPMC/...Y1VFXPXK9M86NP