Selespeed is a touchy subject for some. I think many ppl love it, including me. But it is an extra technological feature and does increase costs. You can reduce costs by learning how to check levels, diagnose and prevent problems. It is necessary to learn a used car's issues and be extra sensitive at first - this is true for all systems.
On the selespeed, you should listen for the pump operation which brings the system pressure to 54 bar (triggered when opening the driver's door the first time after some time off). If the pump is heard more than 12 seconds, the accumulator may be due to be changed in the next 5,000km (not sure).
With the key on MAR, engine off, you can inspect the engine compartment and look for traces of fluid leaks. Meanwhile, you can wait for the next pump movement, triggered when the selespeed pressure reaches low point of 43 bar (something like that). The system should be holding the pressure at least 3 minutes.
I just changed my actuator (£60+labor you see it's not that expensive) and it lasts more than 5 minutes. Before changing it, it was 47 seconds. But if the pump is faulty that's really expensive.
Listening to the pump vrrring, how long it takes to rise pressure. can tell you a lot about the selespeed's state but test driving it will tell you if you enjoy it.
In the UK you can probably take the car to be checked at a small alfa garage. If the mechanic starts by pulling out a cable and scanner or laptop, you're in the right hands.