I am a joes/castcnc builder. I have also built a cncrouterparts machine. Factor in a base and getting a controller togther if you go the kits route. Also think about dust collection, bed and work holding, cable management, etc as well. The kits still leave a lot to build. You will save a tonof money but they will cost you in areas other than money. I love my machine though. I think it offers upgrade paths you would have a hard time adding to purchased machines.
Ridgidness, speed, quality of cut, tooling options - all variables in your machine paired against the requirements of your jobs. The jobs you want to cut should decide your machine.
Glad its my shop I am responsible for - I only have to make me happy.