One word of advise, forget about DXOmark. If Canon user really care too much about the result in DXOmark, we might as well throw our camera into the drain and all jump ship to whatever brands out there.
Note that a camera don't just rely on the sensor alone. It is an entire system, from sensor to graphic engine, to processor to lens system to AF system to whatever other stuff in the camera. A sensor is a big part of the camera but not everything of the camera... and if you are tat particular about sensor, then get the best rating sensor camera from DXOmark lor.
As for how much a wide angle lens cost... you can look at own brand lenses like the Canon lenses, Nikon lenses, Pentax lenses and Sony lenses, or you can look at cheaper alternative like Sigma, Tamron and Tokina lenses for wide angle uses.
Final word, all the camera are the same... they all perform very well, irregardless of what sensor they are using... Canon, Sony, Toshiba and the such. Just get a camera which feel best in your hands and with a user menu that make the most sense, and forget about all others (like I mentioned before, I have used almost all the brands of that offered FF, m4/3 and APS-C cameras out there except for Pentax - oh and Samsung and all of them are excellent.)