I'm a math geek, in addition to many other kinds of geek (C# programmer by trade, and as a programmer you have to know alot of math)

For the curious, I did the math.

Givens:
Each turn-in is worth 75 rep
I need 15k rep (200 turnins)
Each mob has a 17% chance to drop the item
The statistical math indicates it will take approximately 1176 trash kills to gather 200 armaments. Those 1176 trash kills will also give 1176 x 12 rep, or almost enough rep by themselves to get me to exalted. So I'll thus say I'll get half the rep from trash kills and half from armaments, so I need ~600 trash kills. That shouldn't take too long...