I would just break it down into component costs.
Ex. A "special" unit of boring swordsmen with crossbows and a hero
Swordsmen - 6 points each, xbows +2 points each
Hero - 50 points + special weapon (lets say wyrmslayer sword - 15 points), plate mail 8 pts, xbow 10 pts (based on handgun/longbow in profile)
Standard and musician - 15 points + 2 each for xbows
So, your boring swordsmen with crossbows for a unit of 10 would cost
8*7 troopers = 56
standard and mus = 19
hero = 83
Total: 158 points
You may want to add a small premium to the price so that armies need to pay a bit extra to get the unit, so round it up to 175 or something, then +8 per trooper.
That's how I will be making mine. But it won't be boring swords with xbows...