Building from scratch will likely be more expensive than buying the complete Pista. Your big purchases on a build will be wheels and a crankset. Depending on what you consider to be "good gear," these two items alone could set you back $200-300. Then there's all the small stuff that really adds up: Bottom bracket, pedals, clips/straps, handlebars, grips/tape, brakes, brake levers, chain, cog/lockring. It can really get pricey.

On the flip side, when you build up a bike, you're probably less likely to want to upgrade, since you got what you wanted the first time. If you already have a bike, and this is just a project that you can take your time on, collecting parts whenever you have the money, it might not be a bad idea to build up the IRO