Amazon offers a selection of kids' backpacks, with prices starting from $5.92. Plus, Prime members receive free shipping. (Non-members can spend $49 to qualify for free shipping; otherwise, shipping starts at around $5.) A couple of best bets:
Walmart offers this Disney Boys' Mickey Mouse Graphic T-Shirt for $5.88. Opt for in-store pickup to avoid the $4.97 shipping charge. That's the lowest total price we could find for a similar Mickey Mouse shirt by $1. It's available in size 5T only.