Thanks for the info! I wish I had checked back for the "where to buy" update, as I've been looking for a while this morning myself. Although my local Pontiac dealer wanted $45 each for the louvers and $20 each for the deflector/drip pan, I was able to find another online site where the prices seemed reasonable.:
http://www.newgmparts.com/
Search for the p/n's above. The louvers are $31.46 and the deflectors (as they call them) are $8.69 each. Plus shipping of course.