Hiring Mercenaries:
Mecenary prices are all over the place, depending on the market and the skill level.
Most mercenaries want:
1) something in advance;
2) something as a daily rate (although they don't have to be paid every day, you could pay them once a month);
3) extra pay for combat (typically x3 to x7 pay on days they fight);
4) a share of the loot.
#1 is likely to be high for House Millithor, because most mercenaries distrust dark elves. Especially if you don't tell the mercs what the job is, if you just say, "trust us, we'll tell you later." Also, most mercs do not take their advance payment with them on campaign, so you can't count on looting their bodies and getting the money back. Advance Payments tend to be spent on wine, women, and song at the nearest tavern after being hired. For a Goblin, an advance payment could be a gold piece. For a specialist like Chirar or Kilcif, the advance payment could be as much as 10k gold or a magic item or both.
#2 Daily rates tend to be pretty reasonable, and Mercs are used to not getting paid on a regular basis (its not uncommon for the boss to say everyone gets their daily pay after the campaign is over... however, the boss usually doesn't tell the troops this until they are in the field). Goblins might get CPs or SPs per day. Ogres will probably want gold. Specialists might want multiple platinum pieces per day.
#4 Goblinoids want their share of the loot, but when the division of loot comes along, they can be intimidated into getting very little. Ogres tend to be quite greedy when loot sharing comes along.