A full-face helmet from Third Age including OSRS gold, platelegs, platebody and kiteshield together, they can make a more expensive armor set dubbed Third-age Melee Set. The total price for all set is around 834.270.000 RS gold. This set is known for being one of the rarest , most expensive armour sets. It is not like the Third-age prayer sets to wear a Third age melee set you don't need to achieve a higher level in prayer skill. The only ability - defence should be at level 65. The reason for this is that players wear the armor not because they are extremely good or anything in order to show they really have a lot.
The last set of armours to talk about is the Third-age mage set. The price of the set is 256.800.000 RS gold. This set is renowned as the most expensive magic set that is available. In contrast to other sets, the Third-age's mage set comes with an amulet that can be purchased for around 74.60.000 RS gold.
Now you are aware of how much can an armour set cost. In order to earn that much for a unique armour set is going to take a lot of time. If you are thinking about buying an expensive armour set keep in mind that it can be a perfect investment too. In time, you'll be capable of selling it at a greater price.
If you're not able to afford the funds, consider visiting several websites (for example rsorder.com). You'll be able to purchase some RS gold at a decent price , and then put it in Cheap RuneScape gold set.