are you boosting high quantities of gas looking at that unit?
@stuartv basically you get an account with Airgas or some of the local people and get an account. You can choose to rent a cylinder, or "buy" one. If you "buy" one, you don't pay the rental fee, but you almost never get your specific bottle back. With O2 in particular you usually just take it in empty and they give you a new one. On He they usually have to send it out unless you call a week or two a head of time since they don't really stock that stuff normally.
EAN32 is something you MAY be able to get them to get custom for you, but it's going to be spendy. You can get high pressure air from them though which is nice.
Cost is based on your specific account and the specific gases you're getting.
No need for a filter on the outlet of the booster if you're using pre-filtered gas on the inlet. Only time I'd put one in is if you're running it from a shop compressor as inlet gas, but if you're plumbing that, I would also have a direct outlet to bypass the filter since every time you change gas mixes you'd have to purge the filter which is very wasteful.