Andy Woyzbun, Lead Analyst, InfoTech Research Group (www.infotech.com), says:

Ensure that you have some real measures of current capacity and performance, not just impressions. IT must make infrastructure changes to address anticipated increases in capacity and performance. To identify infrastructure gaps, IT must quantify capacity and performance requirements and measure their current capability. It’s hard to align expectations and performance with prudent expenditures if IT is flying blind. Changes should be implemented before poor performance creates user complaints. And IT should avoid overbuilding infrastructure to address non-quantified risks; it wastes money that you (or the organization) could use somewhere else.

Look for cheaper, less functional solutions to get approval. Getting a yes for an imperfect solution is better than getting turned down on a perfect solution.
Technical staff often recommend the best technical solution (greatest functionality and lowest risk) when faced with the need for infrastructure change. They should be expected to identify and examine options that address fundamental needs for no cost or low cost. In some cases, these options will be enough. In others, the analysis will confirm the need for a more comprehensive solution. Improve the credibility of proposals for large scale changes by evaluating lesser options.