Hello! Welcome to Edmunds. Each auto manufacturer sets a time limit for offering direct sale of certain low end replacement parts. There are authorized re-salers that purchase the leftover parts from the manufacturer and offer them to the public. I will list below the two major online re-salers for GM. But if I were in your situation, I would first go to a local independent auto-body repair shop, (one with a good reputation of course), and talk with the service manager about the weather strip they use for replacement. Ask what brands they use and which local supplier carries them. Since they often do repair for people who live in their area, they don't use sub-quality parts and can't afford a bad rep. You'll get accurate honest information, and maybe even make a new friend. Who knows, you may need some ding and paint repair in the future. Nice to have someone you know to talk to about such things and could lead to a good deal. If you still want to just order, the links are below. Good luck!
Answers
http://www.gmpartshouse1.com/saturn/l300/24419435/2001-year/base-trim/3-0l-v6-gas-engine/electrical-cat/rear-door-scat
http://www.gmpartsonline.net/parts/2001/Saturn/L300/index.cfm?action=partDetail&section=BODY HARDWARE&group=TRUNK LID&subgroup=LID & COMPONENTS&component=Weatherstrip&partnumber=24431822&vehicleid=85607&siteid=215055