O Império Klingon usa dinheiro?

Sim. O melhor exemplo que eu conheço é que em "The House of Quark", de Deep Space Nine, é um grande enredo que uma casa está planejando assumir outra por sua riqueza material.

QUARK: Very clever. Very clever indeed. D'Ghor has manipulated your family's holdings, devalued the lands you hold, and he is the principal creditor on Kozak's outstanding gambling debts. It's no accident your family's getting weaker and D'Ghor's family is getting stronger. He's been systematically attacking your family's assets for over five years now.
GRILKA: You mean D'Ghor has been scheming and plotting like a F?
QUARK: Like a Ferengi.
GRILKA: There is no honour in what he has done. If he wanted to challenge my House, he should've made a declaration, met our forces in battle.
QUARK: And risk destroying the very thing he wanted most, your lands and property?
GRILKA: Can you prove any of this? You can show the Council exactly what D'Ghor has done?
QUARK: It's all right there. All I have to do is talk them through it.

...

QUARK: So, as you can see from the gross adjusted assets tabulation in column J, the net value of the land acquisition was actually zero. Now, if you go to the file marked Devaluation of Capital Income, we can review the way D'Ghor
GOWRON: Enough! I don't want to hear anything more about finances, mergers, or currency transactions. The charge has been made that you have used money to bring down a great House. What do you say to this, D'Ghor?

A última citação em formato de vídeo:

De acordo com a Memória Alfa, a moeda klingon é algo chamado darsek , isso também foi mencionado em TNG: Primogênito

ALEXANDER: There's a man over there who's got Molor's head in a box -- the real Molor.

WORF: That is impossible. Molor died centuries ago.

ALEXANDER: I know -- it's mummified. He said he'd show it to us for fifty darseks.

e em Ent: Bounty , onde Archer é capturado por um caçador de recompensas.

ARCHER: The Klingons took your freighter, your livelihood, damaged your relationship with your brother, and what do you get in exchange? Nine thousand darseks. Doesn't seem like a very fair trade to me.