Where you're possibly overspending...
Memory - I'm going to be those people who say get 8GB. If you need another 8GB, then you can get another 8GB. But you won't need more than 8GB until you find something like a 64-bit CAD or media editing program that drinks RAM like a drunk sailor.
Motherboard - Look at all those features and ask yourself are they really that useful. You can get a $150 board with all the I/O as a $300 board (well, perhaps not three GPUs or something). You don't get the bells and whistles, but you have to ask yourself if they're really useful to you.
Fan - You don't need $75 in fans. A $150 case sounds like it's already built with cooling in mind, and with all the fans you could need. Unless you're replacing fans for something a lot more quiet or with more CFM.
Keyboard - A $20 keyboard is just as good as a $100 if we take out all that tactile feedback shenanigans. But to be honest, I don't have a preference for what kind of switches it uses (except those godawful roll-up keyboards). Like everything else, ask yourself, is any of what this comes with actually of any use to you? This is probably something you want to see if a brick-and-mortar store has a display model, so you can try it out yourself.