I was in your position several years ago. Since then I have not purchased a complete bike. I like being able to decide exactly how I want the bike, or at least I want to be the one deciding where to save money. Like @
genejocky, I don't have the tools to install a traditional headset or pressed bottom bracket. I would take those to a local shop to be installed. If you have a carbon steering tube, I would also take that to the shop to be cut (once you are sure of the length that you want.) Apart from all that, it's not rocket science. There are lot's of helpful Youtube videos out there and I also rely pretty heavily on Lennard Zinn's
Zinn and the Art of Road Bike Maintenance. Some frames are very straight-forward and build up without any issues, while others are kind of quirky and might make you have to stop and think. A little patience and some basic mechanical skills are all it takes though.
Make sure you have a torque wrench if you're working with carbon fiber.