Walmart offers Monster Hunter 4 Ultimate for Nintendo 3DS for $18.18. (Amazon charges the same with free shipping for Prime members.) Opt for in-store pickup to dodge the $5.99 shipping fee. That's $2 below our May mention and the lowest price we've seen. (Outside of the deal below, it's the best deal now by $12.)
Of note, with very limited stock varying by ZIP code, Fry's offers it for $17.55 with in-store pickup.