^^ That's actually all really good advice imo, and would be a great starting point. Unless, of course, you prefer SRAM. Also, it's probably not the most cost effective way of doing your build. For example, SLX is a really good value imo but maybe the XT shifters were on sale for the same or cheaper price at the time you bought the SLX. If you want to maximize how much bike you get for your set budget, you really need to have an understanding of the components.
As far as the best places to get deals.. There's Art's Cyclery, Chain Reaction, Nashbar, Pricepoint, Performance bike, Jenson, and a few more that I'm sure I'm forgetting.
Also, welcome to the forum.. And you're right about there needing to be a better resource for doing these builds. It needs to made more accessible to relative newbies, but it's not the simplest of problems to solve.