Walmart offers the Nintendo 30th Anniversary Classic Color Mario Amiibo Figure bundled with the Nintendo 30th Anniversary Modern Color Mario Amiibo Figure for $4.98. (Scroll down to "Buy Together & Save" and click "Add all to cart" to get this deal.) Opt for in-store pickup to avoid the $5.97 shipping fee. That's $3 under our July mention of just one of these items and the $10 under the lowest price we could find for them purchased separately elsewhere.
Also available is the Nintendo Inkling Girl Splatoon Series Amiibo for $5.11. As above, choose in-store pickup to avoid the $5.97 shipping charge. That's the best price we could find by $8.