The cost of a professional automotive diagnostic tool can vary widely based on several factors, including the brand, features, and capabilities. Generally, these tools can range from $500 to over $5,000. 
Entry-level professional diagnostic tools, which offer basic functionalities such as reading and clearing diagnostic trouble codes (DTCs) and providing live data, typically cost between $500 and $1,000. These are suitable for small repair shops or individual mechanics who need reliable but straightforward diagnostic capabilities.
Mid-range tools, priced between $1,000 and $3,000, offer more advanced features such as bi-directional control, enhanced data graphing, and the ability to perform special functions like ABS bleeding or key programming. These tools are ideal for larger repair shops that require more comprehensive diagnostic capabilities.
High-end diagnostic tools, which can cost $3,000 to over $5,000, provide extensive features including OEM-level diagnostics, advanced coding and programming, and extensive vehicle coverage. These are typically used by dealerships or large automotive service centers that need the most advanced and versatile diagnostic solutions.
Additional costs may include software updates, which are often necessary to keep the tool compatible with the latest vehicle models and systems. These updates can be subscription-based, costing several hundred dollars annually.
Ultimately, the choice of a diagnostic tool depends on the specific needs of the user, the types of vehicles serviced, and the level of diagnostic detail required.