Remember that costs involved can vary dramatically.
If you're in the industry or can get materials from someone in the industry, you will find your variable costs significantly lower than someone purchasing all the materials at retail prices. Take into consideration the time you will be spending as well. If you can buy something and start enjoying it immediately, you are getting better bang for your buck even if you spend a bit more. However, if you enjoy doing builds and/or are looking to learn and improve skills, that's another consideration.
You'll find that most people that do large projects like this already have the tools needed, both hardware and knowledge.