Anyway... you need first get a clear idea of what you are going to shoot, then focus on the features that you wanted your camera to have for you to achieve those shots...
Only get the camera that suits your shooting style and genre and not the camera that most people recommend or pressure you to get
The lenses are avaliable for OEM and 3rd party ones, you just need to go to the correct shops (ie. SLRR; MSC; OP; Manly; CP)
~$600 for a Kr body;
~$12xx for a K5 (2011 DPR Gold award "Semi-professional Interchangeable Lens Camera Category")
Don't forget that the cameras come with on-camera shake reduction and all lens mounted will benefit from that (even old MF ones); so its worth the price.
Relax. step by step.
However, the 100% in-viewfinder focus magnification, and the focus peaking, and the 24MP of detail, is awesome for macro work. In outdoor sports/daylight scenarios where you don't need ISO 3200 and above, the pictures are clean, and of course you still get 12 fps and the great AF system.
So you need to know your needs - will you be shooting nighttime action more? Do you need fast FPS? Or are you more of a portrait shooter, or street photography, or landscape? While nighttime action/sports shooting is good, a D3S will be better.
But for everyday shooting, portraits, etc, the A65 will be great. Tons of detail, great dynamic range, etc.
Remember, the A900 sensor technology is 4 years old.
Wow just read Pentax k5 reviews... It's full of love lol
K5 and A65 now...
I'd go with the K5.