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Peters of Kensington eBay are doing discounts on this brand of puzzle games for young kids. Was introduced to these through my son's OT and they're pretty good both in terms of challenge and quality. Most come in a case and therefore good for travel.
Stacks with $5 off $15 voucher for eBay Plus members so the $15 ones - IQ <shape> (usually around $20) come down to $10 delivered after voucher. The $20 ones (Jump It, Asteroid Escape) aren't too bad for the price either ($15 after voucher).
Further stack with cashback/discounted gift cards.
Edit:
FWIW IQ Twist is $12 on clearance at KMart: https://www.kmart.com.au/product/smart-games-iq-twist-puzzle…
Sorry, can't figure out how to generate a link that works to go straight to the search results with only that seller. To find the deal search on eBay Plus items with seller petersofkensington.