Don't assume you can buy your way to end user satisfaction. While the pieces you order might be scalable, there's no guarantee they'll address the constraints you face. Longtime consulting software architect John Cronin sees far too many projects that suffer from backward execution. All of this before explicit system requirements have been established or system capabilities and performance have been analyzed. Even the most scalable product can be deployed effectively only after a solid, up-front analysis.
Systems analysis pays off.
Even projects that look disastrous in the initial stages of analysis frequently hold the keys to a winning outcome. In fact, imminent catastrophe seems to help many organizations clarify their true priorities. If disaster strikes while you're scaling up, make sure you ask the right questions. Model your deliverables and estimate performance. You may find you already have on hand many useful tools for modeling.