Knowing exactly where robots are indoors is very important for swarm robots, especially when GPS signals are unavailable. This paper compares three low-cost methods for indoor localization: 2D LiDAR sensors, RGB cameras, and Ultra Wideband (UWB) sensors. We tested each method in an indoor environment to understand how well they support swarm robot tasks. The 2D LiDAR sensors showed good accuracy when many obstacles were present, but performed poorly in areas without clear landmarks. RGB camera localization was inexpensive and allowed robots to create maps and locate themselves simulta neously (visual SLAM). However, this method had difficulties in poor lighting conditions or in places where visual features were unclear. UWB provided stable and precise localization independent of lighting conditions, although it needed careful setup and faced accuracy issues in areas with many signal reflections. We discuss the advantages and disadvantages of each method regarding accuracy, reliability, and cost. This study provides practical guidance for choosing suitable localization methods for indoor swarm robotics applications.