Remember there is not much point spending so much on an SLR, to only buy cheap lenses. You should be really looking to spend a similar amount on quality lenses. There is just no point in an expensive SLR and cheap lenses. I'd actually be far more inclined to advise you spend less on the camera and more on the lenses.
The cheapest Sony Alpha camera with the best Zeiss lens will take a much better photo than the best Sony camera and the cheapest Sony lens.
In fact, in daylight, the picture quality between a cheap SLR and an expensive one is very minimal. You will have slightly less dynamic range, but thats about it. What you are paying for is low light ability and camera functionality with regards to settings, focus performance and so on.
By the way, autofocus in video mode on SLRs is very much an unsolved problem, even the best Canon SLRs do not perform particularly great with continuous AF. You're pretty much limited to manual focus.