Money

There is not much known about the Klingon monetary system. There seems to be a klingon currency called Darsek DarSeq. (1) Another known unit (probably federation) is credit, in Klingon DeQ. (2)

Useful expressions

Pay now.
DaH yIDIl.

References

1 : Klingon for the Galactic Traveler

2 : Power Klingon