Adding to the aluminium vs fibre cylinder situation:
Standard aluminium 3000psi at about £30 gives you the best vfm, over any lifetime cost it still works out cheaper
Ignore the ability to get 4500psi fills with a fibre as most of the time fills are to 3000psi max
With weight being the usual advantage mentioned the difference between a standard aluminium and a standard fibre isn't that different
Between equivalent sizes the fibre is lighter, but not a lot
More important then weight is balance
(With an ultralight fibre the weight difference is very obvious)
Fibres had the advantage of curved bases which allow you to roll the cylinder in your shoulder. But the cylinder linked above now gives a curved base on a 3000psi aluminium cylinder - a bit more expense at about £40 to £50, but still beating fibre at £150
(You must remember and not let anyone assume it takes 4500psi because of the curved base)
Until you're ready to spend the money on the fibre that ergonomically fits you and a the right size out of the vast range of shapes and sizes then stick to aluminium and consider the curved base aluminium
The gun doesn't care what the cylinder pressure is 3000psi or 4500psi, only the output pressure from the regulator
In early days a £30 or £40 aluminium will do you well, and even if you decide to upgrade sooner rather than later you still have a usable spare or something to lend out
A standard 3000psi will be about 48ci
The price can actually go up a little when the bottle gets smaller in the case of the 13ci 3000psi cylinder, because you're getting something with a smaller market
Fibres will typically be about £150, and the extra money goes into the different design rather than size.
Standard for a 4500psi is about 68ci. So at 3000psi you're getting an extra 20ci of air, then another 50% from the extra pressure when you can get a 4500psi fill
Smaller stubby fibres sbout 48ci, so you get the same size, a little lighter, with the same air capacity or the extra 50% when at full 4500psi pressure
For the majority of fibres the new price is in the region of £150 irrespective of the size, the variation will be for either an ultralight fibre cylinder against a standard fibre cylinder, or for the regluator
A standard 3000psi will be about 48ci
The price can actually go up a little when the bottle gets smaller in the case of the 13ci 3000psi cylinder, because you're getting something with a smaller market
Fibres will typically be about £150, and the extra money goes into the different design rather than size.
Standard for a 4500psi is about 68ci. So at 3000psi you're getting an extra 20ci of air, then another 50% from the extra pressure when you can get a 4500psi fill
Smaller stubby fibres sbout 48ci, so you get the same size, a little lighter, with the same air capacity or the extra 50% when at full 4500psi pressure
For the majority of fibres the new price is in the region of £150 irrespective of the size, the variation will be for either an ultralight fibre cylinder against a standard fibre cylinder, or for the regluator
HI I GOT A MINI FOR MY SON ITS VERY GOOD LIGHT AS HELL HE BEEN PLAY WITH IT FOR A YEAR NEVER HAD A PROBLEM
I would invest on a mini but buy a few upgrades like a flip asa for it, youll still have more money left over than you realise but jusy still use an aluminium tank for now and keep the rest of the money to keep on playing 
