The most expensive of them is the RS gold Cape of Skulls. Although this item owns identical stats and base stats to Obsidian Cloak, it also has a distinct appearance and is sought after by a lot of players. That's why this cape is priced at more than the 20 million mark. There are also capes with gold values of over 1 million, gold-trimmed monk robes , with values of a few millions, and many other set pieces that cost as little as a few hundreds of thousands of gold.
Medium Clues are probably most common among the RuneScape community since they provide excellent rewards, but not as very high of requirements. Of the numerous items you can find inside them, the most notable drop which deserves to be recognized is the pair of Ranger Boots. This item is valued at more than 30 million gold on Grand Exchange. Although medium clues aren't as likely to have the same high-priced rewards such as the easy scrolls are, they do have a better chance at Ranger Boots than Easy Casket does in Cap of Skulls.
In addition you'll also get higher rewards for opening Medium Casket than you would with a standard one (so you can expect things including shield h3, H2, or the helm the h3). Apart from being able to find Ranger Boots in a distinct drop list, you will also get cheap OSRS gold Spiked Manacles that cost over 1 million. The other rewards aren't as valuable as these two items.