About competitions. We hardly have one or two every year, and since aerobatics is not a big thing here and not too many people participate, the government pays for most of the expenses, including ferrying and insurance.
LePaul: About taking the plane for a weekend... well, if you plan in advance, I doubt there would be problems unless it interferes with trainings for a competition.
In the club where I fly, if you are flying more than 2 hours (engine time), you can have the plane for a day. There are some planes excluded from this rule so that the entire fleet is not away at the same time.
That can be done because the fleet is quite large (28 planes including 172N, 172J, 182, PA28, PA27, C310, Robin 200, Tecnam P92JS, and a couple of aerobatic airplanes, a CAP10B and a Zlin Z-50, which I have to test in flight before making a decision on the Pitts).
There are also some historical planes that can be flown if you are really interested and with experience in taildraggers/aerobatics. Right now I'm learning to fly the Dornier 27 (hell of a beast), but there is also a T34 Mentor, a Boeing Stearman, 2 Bücker Jungmanns, and a couple more.
Bluefish: Thanks for the info, I really hadn't taken into account the parachutes. The ones in the Pitts are not old, but it's another cost to add, nevertheless.
Hangars are not as expensive as in the US because aviation is not such a big thing here... for better or worse.
Daniel