You get you what you pay for with the Canon EF 200-400mm f/4L IS USM Extender 1.4X: superlative performance and flexibility.
The Canon EF 70-200mm f4 IS USM L lens is a professional grade 70-200mm lens without the size and heft, as well as price, as found in f2.8 versions.
The Canon EF-S 18-55mm IS kit lens is a solidly performing medium-zoom lens, with good optics and image stabilization, that will appeal to more than just the entry-level crowd.
A fine camera, the Canon EOS Rebel T4i's more expensive 18-135mm STM kit (or body with another STM lens) is the only version that merits an unqualified recommendation. You can probably find better alternatives if you just want a sub-$1,000 dSLR for still photography.
Sony's Alpha DSLR-A100 deserves consideration whether you're looking for an alternative to Canon and Nikon, you already own a selection of Maxxum AF lenses, or you're looking for your first digital SLR.