The last PDF I had showing FLASH upgrade list pricing for an APX 6000 is at least 4 years old, so outdated at this point. Anyway, the states almost always have contract pricing lists online, which shows both the list price and discounted contract price. They are not hard to find, so I would suggest doing some searching if you're that interested.
Is there anything in particular you're looking for to actually have upgraded, or is this just a general curiosity question? Note that MSI does not sell FLASH upgrades for the APX series to the general public, you would need to go through an authorized dealer, who also might not give you the time of day for a one-off upgrade to a personal radio.