My 12L 232 bar tank will only fill to just over 3000psi when full, and soon drops to 2500psi or less. It really depends on how empty your gun bottle is - filling from empty really robs the dive tank of pressure. When we take our own air to sites we usually have 4 or 5 tanks on the go, and fill from them in sequence eventually topping out from a 300 bar tank. That way we dont kill the pressure in the fill stations at the same rate, and always have enough in the 300 bar to top the guns up to full.
If a few of you have rigs it's worth pooling your air like this, as you get more fills during a full days play. We use 2 tanks to bulk fill to about 2000psi, and then top up 500psi each on the remainder to finish at 3-3.5K depending on bottle.
My local dive shop charges £4 to fill my 232 and around £40 to re-test. I bought the bottle on ebay for £60 3 years ago, and my A-clamp fill rig set me back £35.
