1. ebay, search on lexus ES or lexus ES lights.
2. used, www.car-parts.com when putting in your search info., remember to search for an 01 ES not a 98. This will bring up salvage yards, and many are in the NY/NJ area. You may save on shipping that way.
3. new, www.newlexusparts.com when putting in your search info. click on collison not mechanical.
good luck. I too am in the middle of a model year taillight swap. 05 tails going on an 02.
steviej