Salam Gentlemanrambo. The trip costed about Rs 500k in total, including the gear - we purchased all the high altitude equipment as Ahsan is an avid mountain climber and goes for climbing every summer. The duration was 1 month. Please note that the cost is for a Summit expedition. The costs for a Base Camp trek should be significantly lower.
There are numerous websites on the internet of tour operators from Skardu. You can get updated information about costs to K2 base camp by sending them an email. These tour operators are very efficient and generally reply within a day. Some tour operators have facebook pages also.
A gentleman from karachi has put up an excellent travelogue of his trek to K2 Base Camp at the following link, which should provide you an excellent insight:
K2 Base Camp Hike - 4x4 Offroaders Club Karachi
Please let me know if you require further assistance.
Good luck and please keep us posted via this wonderful website.