VR simulator
I recently bought a bunch of stuff to build a VR simulator - big honkin' PC, oculus rift, hotas, stick, and even a cool seat. Probably about 4k of stuff. The goal was to get more comfortable with the rudder on the ground, since while I have a tailwheel endorsement, I didn't feel that comfortable.
I use DCS world with the p-51 and the Christen Eagle.
I'm pretty impressed with how it handles - even though it might not be truly accurate to the aircraft, it's helping me tune up my rudder skills.
With the VR headset and the powerful PC you can look around, and it looks very real.
The only part I don't enjoy is if I crash, I get a bit seasick, since the plane is moving in a strange way visually, but there is of course no motion on my chair.
I have done very little aerobatics both in the real world and VR, so I can't say if it's realistic or will help you, but it seems very good to me. It's certainly fun.
I'm also practicing things that are hard in real life, like engine failure right after takeoff. It feels very real, and I believe it's helping to instill the instinct to get the stick down, and don't stall/spin/crash/burn/die.
I justified the spend since an hour in our club's tailwheel aircraft is about 300, so 15 hours of sim time pays for the whole setup. Also, in the sim you can focus on the stuff you want to practice repeatedly, and can do it any time in any weather.