Walmart discounts a selection of Funko Pop! figures, with all priced at $4 or less. (Amazon charges the same for many of these.) Shipping adds $5.99, but orders of $35 or more bag free shipping. A couple of best bets, provided you take advantage of free shipping at $35:
Funko Pop! Games Tekken Nina Williams Vinyl Figure for $3.99 (low by $4)
Funko Pop! Movies The Lord of the Rings Gollum Vinyl Figure for $3.99 (pictured, low by $4)
Making even one of these mistakes can easily cost you tens of thousands of dollars.