I'm sure I'm not the only person to have lost one of those plastic air box clips. I asked about a replacement at my dealership and was told I'd have to spend $75 on a new lower half of the air box. That was pretty unbelievable, but I had a lot of trouble finding the part elsewhere.

For the benefit of the community, I give you the part number. 17219P65000
This fits my 2011 Fit Sport.

There's also a CAD file at http://www.thingiverse.com/thing:14947
in case you want to print or order some 3D printed parts in snazzy colors.