Pirke
How would you suggest to approach searching for an aircraft with the intention of buying it and flying aerobatics in it? As always, budget is a limiting factor, but I'd rather wait a few more years to buy something reliable than to throw it away or worse: have an accident.
As already said most if not all civilian aerobatic aircraft do not have a fatigue index measuring device but use a method of calculation from hours flown. Therefore buying a second hand aerobatic aircraft you will never know if at some point during its life it has been overstressed where as a fatigue index meter will record those very high "G" counts, once I remember seeing an 8g recording on a Jet Provost
So ultimately if you want to feel safe about the wings staying attached is to buy new.