Please PM me the #resnumber where you can get glowstone for 10r each, because I haven't encountered such shops yet! Edit: *throws around some confetti*
I never said I know where it is, but that is the minimum I would pay per stack of glowstone, therefore the price of 2 DCs is minimum 69k
I would think any where between 15r at the very lowest and 25r each block, at top price, but I have not bought or sold this in a long time so I may be slightly out on it. Past averager for it was 22r each. Based on 22r each 22 x 3456 = 76'032r for 1 DC or 152'064r for 2 DC's