I don't think Tourism buses takes any big chunk of budget since not many buses are inducted for such purpose. May be fleet of 10 buses would be more than enough and that may cost only 5-10 crore rupees?
Having said that, there was no need for such initiative for war-torn country. You are being blown up by the terrorists, the foreign tourists don't want to come to Pakistan and you are introducing such buses? I think locals are going to enjoy taking a ride in these buses but don't call it London or Barcelona like models since they are mostly focused on foreign tourists.
You sort out the terrorism issue first and then go for such perks to increase tourism. If terrorism issue is not resolved, this is just a waste of money