I'm assuming you only want 2 non-dual-duty constants for that price.
Altador Cup Throwing Star, Bow of Destiny, Wand of Reality, Brynns sword, Yblaster... etc the 13 iconers.
sloth duck (14 icons) + scroll of knowledge
any 13 iconer + scroll of knowledge
HCC blocks 100% dark and does 10 icons.
RP blocks 5 physical and does 11 icons.
They are the only DDs are worth it.
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The only other 2 that are worth mentioning are "Stocking Full of Coal" and Portable Cloud (PCloud).
The stocking only does 9 attack and blocks 5 light however, and is pricey at the moment.
PCloud is the best DD aside from IStaff/WoDF, but costs 7-10m.