Fry's offers Nintendo Selects Mario & Luigi: Dream Team for Nintendo 3DS for $19.95. (Best Buy charges the same via pickup and Amazon the same with free shipping for Prime members.) Opt for in-store pickup to avoid the $2.99 shipping charge. That's the lowest price we could find by a buck.
Also available is Nintendo Selects Kirby: Triple Deluxe for Nintendo 3DS for $19.95 via in-store pickup. (Best Buy offers it for the same via pickup and Amazon the same with free shipping for Prime members.) That's $4 under our mention from last March of the non-Nintendo Selects version and the lowest price we've seen for the game. (It's also the best deal today by a buck.)