User blog comment:DamonDraven/Oh, dear Reaver.../@comment-10958553-20141214225826/@comment-35229418-20141215162225

Nah, if that was the problem, ER would have been bought when its cost was of 2600g. And it's already very cost-efficient: while I didn't put it in the calculations, assuming the mana restore's value is the same as the 10% life steal (because otherwise the toggle wouldn't be worth it), the total effective gold value would be of 3927g (10% ls=550g), which surpasses Bloodthirster's gold value while having a lower cost (300g less).