This is a question that is asked frequently.
These are the factors too take into account when choosing your camera.
The two best DSLR/SLR (Professional Camera's/Big Cameras) brands are Nikon or Canon.
You cant just get "The Whole Kit" there are a variety of lens that cost from £100-£8,000+
depending on what you want too shoot. Besides lenses there are toones more accessories for your DSLR/SLR camera, you can get filters, tripods, remote controls etc.. theres everything to fit your needs
Looking on the canon side, this is how it works.
The first series of canon DSLR/SLR cameras are the beginners stuff. These are the 400D 550D 1000D 500D Etc..
The next series is the mid range Serious stuff but not quite pro.
These are the 10D 20D 40D 30D etc..
The next series is the high quality professional stuff
These are the 1D 5D 7D etc...
All DSLR/SLR take high quality images but the pro stuff like 1D has more advanced settings.
I'd do a lot more research before you decide on buying any DSLR/SLR and only buy one if your dedicated to the hobby and you are going too keep it up. Dont spend loads of cash on something you wont use!