Startup cost: $100 - $2k

Low-end estimate: Setup costs range from $100 to $500. High-end estimate: Setup costs range from $500 to $2,000. Explanation: The money would be spent on basic window cleaning tools such as squeegees, microfiber cloths, a bucket, a scrubber, and cleaning solution. Optional expenses could include a water-fed pole system for high-rise windows or a professional window cleaning belt. Hidden costs may involve transportation fees if you need to travel to clients' locations. Recurring costs might include cleaning solution refills or replacement tools. Overall, the initial investment for a window cleaning side hustle can vary depending on the scale and equipment needed.