Not sure on stock replacements but they're typically kinda expensive, most people just jump for projectors because that seems to be one of the gripes of these cars, crappy headlights.

1997-2003 GRAND PRIX PROJECTOR HEADLIGHT 1998 1999 2000 on eBay.ca (item 110455927612 end time 10-Dec-09 00:22:41 EST)

Ebay is the cheapest place to get them.

its two 10 mm bolts then they can easily pop out.

Good luck with that!