Buying/Selling car parking space in CBD

I plan to buy an apartment in Brisbane CBD. The affordable units that I'm looking at do not have a car park. This is not a deal-breaker for me at this time. However, I imagine that I may want to get a car at some point in the future.

My question is, does anyone have any experience with buying/selling car parks in Brisbane CBD? Assuming someone wanted to sell their car space to me, how difficult is it to do this process? Does a car space always have to be attached to an apartment? I know it's always an option to buy/rent a car spot in a dedicated parking tower. I would be more interested in buying a car space in the apartment building in which I buy an apartment.

This post may also fit in the ausfinance sub, so I may also post this there. If you have experience with this process, please chime in. I'm keen to hear from past buyers/sellers and also conveyancers that have provided this service.