If it's OE sunroof search your local salvage yards and if that fails get online and search salvage yards. This will be your cheapest route. Dealership will want a small fortune for a replacement. If you do have to go to a dealership give them your VIN No. they will be able to look up the exact part for your car.
RepairPal Certified shops can diagnose and repair your 1993 Lexus ES300. They provide transparent pricing with a minimum 12-month or 12,000-mile warranty on repairs and services.