OK, here something I found out. I looked into YAK 52's. No, I'm not going for one, but it seems maintenance costs are the same as the 150. A new engine for the Yak is $23,000, 0-200 is $22,000 about. Overhauls are 12,000 for both for example. The Yak is experimental exhibition, but most of my aerobatic flying would be close to my airport anyway.
Maybe a Yak could be in my furture in 5 -10 years (I would still keep my 150 though).
Steve