From what I recall reading, Watts = Volts X Amps. I am trying to figure out the most cost effective lithium-X module/battery to get/build in any combination that gives me 3,000 watts.

I looked around a bit and didn’t see anything so before I start data gathering and calculations does anyone have any numbers or references for the most cost efficient way to achieve 3000 watts via Volt and Amp combinations?

For example:
72 Volt 42 amp hour average cost is X
48 Volt 62 amp hour average cost is Y
36 Volt 84 amp hour average cost is Z