There’s nothing wrong with you taking the a5, but it’s worth looking at options.
I still have my old X7, but it’s the ‘always reliable’ that I have used and chucked in the cupboard.
It’s only had any internal clean up by Tippmann tech, and the year before last was its worst state with a broken cocking handle and rust due to having been stored since sennybridge for many years.
Saved by tipmann tech again, with some parts swapped and a polish.
I would avoid co2. The cylinder is cheap, but the chances of you getting a fill at anywhere but a rental only site are slim.
For a cylinder you can still go cheap with a basic aluminium 3000psi air cylinder for £30 to £40 new
Even better is a fibre 4500psi cylinder, but that would set you back at £150 or more new. Save that until you have the experience to know what size fibre is the best fit for you physically and for style of play.
For a hopper unless you get a cyclone fed gun (a5, x7 etc) then you ideally want an electric hopper.
You can still use a cheap gravity hopper, or a ‘shelf’ gravity hopper would be a bit better.
An electric hopper can be sourced for not a lot of money such as a rotor or halo.
Spend as long as you are willing to do so researching and posting questions / options and you’ll gain classifieds access soon for an informed decision on a second hand bargain