I saw the original item seller here, but I thought: "This waste a LOT of cycles and could be smaller in terms of coding", so here it is: This block sells your item box for some amount of coins. First advantage: it uses RAM $13CC rather than CLCing and ADCing to $0DBF. BUT this isn't the only thing! I included a Item Seller that is compatible with Item Box Special Patch (the huge table is needed).
No credit needed, as it was easy to code. Just remember to set it to act like tile 129.