The mass-produced plastic keychains, fridge magnets, and "Tokyo / Kyoto / Japan" tourist trinkets near the entrance are typically made cheaply in bulk and priced far above their value. You'll find identical items — often literally the same product — at department stores, 100-yen shops, or actual souvenir shops at better prices or higher quality.

Generic phone cases and cables at Donki are often marked up compared to what you'd pay on Amazon Japan or at a dedicated electronics store like Yodobashi Camera or Bic Camera. Cable quality in particular can be inconsistent. For character or anime phone cases, Donki is fine — for basic protective cases, shop smarter.

Pre-assembled "Japan snack gift sets" near high-traffic areas in Donki are often marked up 30–50% compared to buying the same items individually from the snack shelves further inside. A set labelled ¥2,000 might contain items that cost ¥1,200 total if purchased separately. Always compare before grabbing a pre-made set.

Many tourists buy popular Japanese medicines (eye drops, pain relief, cold medicine) without understanding the ingredients — some Japanese OTC drugs contain substances that are restricted or illegal in other countries. Additionally, Donki's pharmacy section prices are not significantly cheaper than dedicated drugstores (Matsumoto Kiyoshi, etc.).

Unbranded "smart watches", cheap bluetooth earphones, and no-name gadgets at Donki may seem like bargains at ¥1,000–¥3,000 but often have short lifespans and no meaningful warranty — especially problematic when you're back home. Also, Japanese electronics may use 100V plugs that need adapters for 220V countries.

Donki's clothing floor can have gems, but most items are fast-fashion level quality at mid-range prices. More importantly, Japanese clothing sizing runs significantly smaller than Western sizing — particularly in shoulders and waist. Impulse clothing purchases often result in items that don't fit when you get home.

While Donki is generally great for cosmetics, some items — particularly mid-tier domestic brands — are actually priced the same as or marginally higher than nearby pharmacies (Matsumoto Kiyoshi, Sugi Yakkyoku). The visual chaos of Donki's store layout can make anything look like a bargain by comparison. Always spend 2 minutes checking pharmacy prices on key items.