Its a difficult question whether PN can afford a carrier on not
One reason is the lack of funds available to purchase Aircraft carrier . An AC will cost a minimum of 1.5 Billion USD and that too a 30000ton one , something like the Nimitz can cost as much as 5 Billion USD
Second is lack of available escorts for the carrier . At present PN operate like 9 Frigates and zero destroyers , out of which 6 Tariq class Frigates are like 32-37 yrs old , 3 of them would be decommission by 2016
Even a Small CBG like the one operated by India comprise 7 vessels
Like 2 Rajput/Delhi class Destroyers , 3 Talwar/Godavari class Frigates , 1 Kilo class Sub and 1 Tanker
Even if Pakistan was to acquire 2 Destroyers and 4 New Frigates , it still cannot afford to have half of its Surface combatant forming part of CBG , coz that will leave quite a small number to defend its coast
Before acquisition of a carrier PN should look at acquisition of 1-2 Second Hand LPD like INS Jalashwa to get experience in operating large ships , and the fact that LPD can carry out Humanitarian operations in time of crises like Tsunami , Earthquake , Hurricane
If u look at the fact that India got a 35yr old , 17000ton LPD capable of carrying 6 Helicopters and 1000 marines for only 52 Million USD , while Pakistan is Paying 78 Million USD for a 33 Yr old 4000 ton frigate
This tells u who has got a better deal and who has got a raw deal
USA has like 4-5 Trenton class LPD which would be decommissioned between 2012-16 after 40 yrs in service becoz of Induction of the San Antonio class
U Guys can also look at South Korean Dokdo class LHD which cost around 600 Million USD but can carry like 10-15 Helicopters along with 720 marines
If u guys insist on a platform capable of supporting fixed wing aircrafts then u can try convincing the US to Sell one of the 2 Tarawa class LHD/Harrier carriers like the USS Nassau WHICH WILL BE UP FOR DECOMMISSIONING IN 2015 , after 36 yrs in service
Now this ship can carry upto 20 Harriers and 10 Helicopters along with 1900 Marines and it will not cost more than 300 Million USD u can spend another 150 Million USD on 15-20 Second hand harriers and replace them with F35B when they become available to u after 2025
If u want something smaller and also cheaper then u can request UK for HMS Ark Royal before it is sold to some Turkish company as scrap metal , Now this ship is only 25 yrs old and was suposed to remain in Royal Navy service till 2016 Till the SDR screwed it up
I am sure Royal navy would be willing to sell it for about a 100 Million USD and u can spend another 100 million USD on purchase of 12 harrier