Replacing a shower cartridge is a moderate DIY project accessible to homeowners with basic plumbing knowledge. The DIY approach costs approximately $50 to $120, covering the replacement cartridge and necessary tools like wrenches, screwdrivers, and plumber's grease. The process requires turning off the water supply, removing the handle and trim, extracting the old cartridge, and installing the new one. Success depends on correctly identifying the appropriate replacement part and following proper installation procedures.