It will nearly always be cheaper to get an airline flight
So any "costs" debate will always be intractable.
If you can
easily afford sole ownership, go for it (unless you will be flying too little for the engine).
If you cannot afford sole ownership, then you can't do it
In between the two, you get different positions where people try to argue that £200/hr or whatever is too much and renting would be cheaper, etc. But you cannot go away anywhere and rent. Look at the trips I do... I could not do most of them if renting, due to the time span. These long trips represent only a fraction of my TT but they give me a huge benefit; without them I would just be messing around in the UK and most of those flights can be
driven in less time.
It is important to be able to
easily afford one's flying. If the affordability is marginal then you can be subject to family pressures bordering on resentment (depending on how good your relationship etc is).
Anyway, I gather than the SR22 "hour block purchase, zero equity" setups charge about £250/hr, which is a lot. Unsuprising, because they let just about anybody with a PPL to fly it, and they are set up to make a profit for the operator.