As a pilot I can tell you that what you call "top real flight sims" are but a toy compared to the real thing. X-Plane is IMO better than Microsoft FS9 but it's not realistic in all aspects.

X-Plane likes to tout their system as being so close to real life that you can model a plane in it, go build it and fly it the same. Ever hear of the Atlantica, it was designed on X-Plane and did fine in the sim. They company made a big deal of modeling it in x-plane and built it, then crashed it. They never progressed beyond the initial crash which showed it was pretty unstable and nothing more has been heard from them since April of 2003. It did fine in X-Plane, I in fact flew it in X-Plane and it was solid. Real life proved X-Plane was not accurate enough. The flight by the way was not intended to happen, but as I was given the understanding it was so unstable that the thing took off before it should have, or it was going to crash big time. Nice plane and I wanted one.

I have flown personally several of the planes that X-Plane models, they do not handle like the sim portrays. FS9 is even worse than that.

Those $50 sims as you say, and X-Plane is normally more than that and the upgrades are for the version level you buy into, they are not realistic in my personal experience. I own both FS9 and X-Plane, and a Cessna 150, and have flown every Cessna from a C140 to a C182 and they do not fly like the sims as you believe. So if you buy X-Plane 7 now, and it's worth every penny of the $25, you will not get X-Plane 8 for free. Not if Austin behaves like normal. It used to be if you bought into version 6, when 7 come out you had to buy it again. But you got every version of 6 he made, and he made lots of version of 5, 6, and 7. IMO best sim out there, but not accurate enough compared to real life, but it's close.

Sorry, unless you just want to practice flying on instruments and can ignore the unrealistic behavior it's not as close to the real thing as you've been led to believe. I've griped for years to Austin that it isn't modeling a simple slip accurately as have many others, and it got worse with every version until I finally quit buying into the new versions because he was adding eye candy and not fixing the flight model. It for a long time couldn't even do a loop and he finally tricked it out so it could, but it wasn't accurate because he tricked it.

By the way, when I first bought X-Plane it cost me almost $200, and others paid more than that for it. You get what you pay for.