you get what you pay for. the difference between PAC and most bags is PAC uses three layers of material throughout the bag. the liner between your stuff and the truck tarp makes the bag last a lot longer.
if you were to ask for a quote from any bag maker for similar size and options it would probaby be at or more than PAC is charging. and PAC has been making these bags long enough to know what they are doing. and in spite of the complexity of all the straps it is easy to use and makes for a much more comfortable, versatile bag.
while some things in the bike industry have high prices for other reasons (exchange rates: rapha; rarity: njs) the high price of PAC bags is because of the quality of construction, and the time and thought that is put into the diesgn.
the reason for this diatribe is i don't think people should act like someone is a fool for paying that much for a PAC.