VictorVictorBulloch via eBay offers these MLB Unisex Team Logo Flip Flops in 13 team options for $8.99 with free shipping. Outside of the mention below, that's the lowest total price we could find by $6. They're available in sizes XS to XL, although not in all team/size combinations.

Of note: Avalanche Brands via Amazon has them from $7.04 with free shipping for Prime member in select team/size combinations.