This is the route I went - my 2007 Colorado only came with an AM/FM radio and the knobs didn't even work right.
You can shop around on Amazon for a better price on stuff but I chose Crutchfields for ease of ordering :)
Installation took about half an hour taking my time no hurry.
I have to agree regarding Crutchfield. I've used them for more years than I care to list and have never had a bad experience with them. Their support techs are also great. Extremely knowledgeable and patient.
I recently replaced my stock radio in my 2008 Canyon with Pioneer model (AVH-X2700BS) from Crutchfield. Very simple install and perfect options for my needs.