Don't be a lone ranger
One of the fascinating things about networks is that, to achieve any given desired end result, there is always a virtually limitless number of possible approaches. That makes seeking a second opinion on your proposed solution to any given challenge an absolute necessity.
Whether you need to upgrade, replace, modify, extend or reconfigure your network, there will always be many different possible ways of doing it. Only one of them will be the best approach for your particular needs. Tackling the problem of nailing that one down on your own is a tough challenge.
I love challenges like this - they are like a complex puzzle that needs to be solved. And they come up frequently, in all sorts of circumstances. Maybe a solution designed for a particular scenario doesn’t work - perhaps the details from the original network starting point aren’t right, there's been a change of WAN connection or a last-minute change of software that the hardware doesn’t support. Or maybe there's less budget or physical space than had been expected.
In such situations, changes must be made, and selecting the best changes is made vastly quicker, easier and more effective by securing an expert second opinion. Viewing the situation in a different light and from a different perspective usually turns up unexpected options that would otherwise be overlooked. And those options can sometimes save thousands of pounds and untold effort.
Working from those options, you can then create lists of the components needed for each one, and cost them up. One of those quotes will be lower than the others, for the same end result, and there's a good chance it will be one that you hadn't previously considered.
For this reason, whenever I propose a solution I always offer at least two alternatives for the customer to consider - this is particularly important in the current economic climate. For example I will often offer two single-port modules in place of a single, more popular dual-port module. The laws of supply and demand dictate that the former is nearly always cheaper than the latter.
This approach is particularly invaluable in situations where a proposed network solution is beyond the scope of your budget. An expert second opinion can almost always deliver canny ways of removing cost from a quote, potentially using products from completely different ranges. This is especially so when a network design has been over-specified in an attempt to cover all eventualities - I can almost guarantee that there will be a cheaper alternative just waiting to be found by a fresh pair of eyes.
Don't go it alone. Always seek a second opinion.