Building your own bike tends to be very poor value (IMO) compared to buying "complete" - unless you shop around for deals, both new and second hand.
Consider that this shopping-around might result in changes from your "ideal" spec, depending on whats available/on offer when you are looking. So you might not get exactly what you want components-wise.... which is one of the main points of building your own.
It's pretty simple to spec up a self build to see how much it would cost - then compare it to the likes of Canyon and YT (as an example of best-value ready-built).
For me, for 3K, I would be looking at either the canyon nerve, or maybe their new carbon strive. They haven't got the prestige of a Yeti or SC, but I'm not bothered about that.