I would probably wait..
I am no expert at these things, but I suspect that the reason Barrows items are rising at the moment is because of the "new look" of these armours, and so alot of people who previously did not own sets of Barrows armour are now trying to scramble and get a set. This high demand for the armour causes the price to rise.
During the next week though, there is going to be MORE Barrows armour than ever coming into the game because of the increased drop rate, and the chance of recieving x2 loot from the chest. Once things calms down a bit and everybody gets used to the new armours and the increased loot bonus is over, the price should drop back down to what it used to be, and probably even a bit further as the demand for the items decreases amid the steady supply. So personally I would wait it out a bit longer.