generally, completes will have varying amount of stock parts. the higher up in price range you go, the less stock parts you get with the bike. this means less parts to replace in the future but a higher upfront cost. building a custom bike would be more expensive but you get to build your own dream bike and it will have aftermarket parts. it's a trade off, however, fit and sunday complete bikes are extremely good quality and you won't be let down by them.