Pitts advice
Go ahead and make a ridiculous offer on any single seat pitts. They are not moving on the market. If a guy needs the money he will sell. Most guys can't afford to have one and maintain it to standrads for very long. See note below.
Always plan on overhaul being well less than TBO, for all listed reasons. C-172 and C-152s at a flight school may make overhaul, but a rarely flown airplane that is ran hard and flown through aerobatics is a different animal.
Buy the best airplane you can. Maintenance is extemely expensive. Recovering th plane, rebuilding a wing, and working on an engine add up. Down time is what will kill you though. Trying to find a guy to work on a Pitts or any fabric airplane is tough, and these guys cahrge a premium unless they are your buddies.
Only a fool or a wealthy man owns an airplane outside of a partnership. Find a few expert pilots and poney up on a Pitts together. Seek out the best two seat training for your partners and require recureent checks. Good Luck
Former Pitts S-1S owner
PS. I bought and sold my Pitts S-1S for around 25K. Spent quite a bit on hangar, routine mx, insurance, and gas. I figured 1900/yr for insurance, 3000yr for hangar. 1000-3000 yr for mx, and 4500yr for gas/oil.
10-12K a year to own and operate my 25K Pitts with no major mx issues. 100 hours per year. I later dropped full coverage (liability $600/yr). You might be able to reduce hangar or mx expenses. Maybe get it down to $5-6K per year. Good Luck.
I now own a 2004 Super D, and it runs about 23K a year for paying the bank and all the above listed expenses.