A shelf for my center channel speaker?

Keep it below, not above. I have a sound anchor stand you might be interested in.

These from West Elm might work.

http://www.westelm.com/products/s-wall-shelf-p191/?pkey=cwall-shelving

http://www.westelm.com/products/bracket-shelves-w320/?pkey=cwall-shelving

Diofan,

I bought a shelf that works well at a home improvement center (Lowes or Home Depot,forgot which one). The supports are attached to the studs but are not visible once the shelf is in place. It's very sturdy and I think it looks pretty good without the visible supports. I believe it was less than $40 and they have various sizes. You can see a foto by clicking on my "system" tab below. Hope this helps.

Diofan,
Forgot to mention that you'll need to find a method to tilt you're center channel downward for better sound dispersion to listeners. My cc has adjustable front and rear legs so it was easy. If yours doesn't, you'll need to get creative. Good luck!

You can use rubber wedge door stops to angle the speaker up to your listening position and a laser pointer for accuracy after you decide on the self.