This is one of the most original ideas I have seen to RuneScape gold reimplement dueling. I like the notion of a grand exchange-like system, and it causes RWTing to be very insecure. However, Real World Trading could still be possible, and also there are several tactics to circumvent the machine.

The largest problem I see is the staking of things. A player buying a blue phat from an illegal RWTing sight might face some trouble getting their dealer in a duel, but a player who requests a stake of a blue phat, adamant warhammer, and red bead might not. This combination would be quite so random and unlikely there would be little to no possibility of the player not obtaining the RWTer he is purchasing from within a duel.

The best method to prevent this would be to simply allow certain things to be staked, or to not allow stakes of multiple items. Money might be staked, and common things such as whips, phats, ans h'ween masks (items traditionally staked), however the amount would be pre-set (players could not wager strange amounts like 4,397,031gp) and uncommonly staked items like colored beads couldn't be included in the same bet as big amounts of money or rare/expensive products.

Another problem I see with your idea is that many players wouldn't enjoy the risk of it. Because you would not be able to see exactly what armor your player was wearing, if they were ranging or maging, or even their exact level (your thought outlines a set of close levels, but maybe not an specific level) players might be scared to bet large amounts, because the level of the opponent says very little about them.

You may have followed us this far, but your trail ends here! The Mage of Zamorak and Taurus will teleport away, leaving you to battle four level 103 vampires (it will be multi-combat). Among the vampires, however, will throw blood rush on you, but won't cure himself, but buy rs3 gold rather the vampire using the most damage taken. Slay all of the vampires. There will be a brief cutscene.