I have a compressed air tank that's empty if i take it there could they fill it up and how much would they charge?

If is for airsoft give them a call. Because as far as I know even tho their website states a price for air I belive that polarstar like weapons have been banned. If is for paintball, then they do offer single fills for 7 or all day for 11. But some of the entry fees cover the air refills.

You manually refill your tank for free all day as long as you pay for all day air which comes included when you pay to play