If you want a company to purchase tools for you to do you job, you need to tell the company what the cost will be if you do not have the tools in place.
This will include the cost of your time to perform the job without the proper tools. It will also include the potential costs of any issues that arise from not have the proper tools in place, like the cost of a security breach or maybe loss of clientele if a security breach occurs.
Basically you try to present what it cost to go without the tools you need and all of the issues that come along with that, and then compare that to the cost of buying the tools.