If you guys go on yourself, you can even manage this trip in less than 10k per head.
Lahore to Pindi via Niazi = 700 per head
Pindi to Raikot via NATCO = 1500 per head
Raikot to Tato Jeep (Return Journey) = 1500 per head (6000 total divided by 4)
Hut At Fairy Meadows = 750 per head (1 hut for 2 days at 1500 Rs)
Meals = 3000 per head (around 500 per day per person for 6 days)
Raikot to Chilas in some private transport & then Chilas to Pindi via NATCO = 1700 per head
Pindi to Lahore via Niazi = 700 per head
Total per head = 9,850
Can be even less if you can ration the meals and camp instead of renting out the huts.
With above plan, You save around 5k per head, that means a total of 20k would be saved among your 4 friends.
Adding Hunza would be better if you really have to but if its your first time then Fairy Meadows only is just ok too.