I have built bikes from the frame up, not frame building. Here is what I have found... unless you have or can transfer a lot of parts from another bike, or you get an unbelievable deal on a frame, it will cost you more, and maybe a lot more if you make mistakes, to build a bike. Also, if you want to build a nearly identical bike as one you can buy, save your money and buy a complete bike. If you want the experience of building a bike, take everything apart and it back together. At least you'll know everything fits.
Building a bike is always better if you can't buy a bike the way you want it to be and you have to spend money anyway on replacement components.
If you decide to still build a bike, you have to do your research. Pick a frame that will fit your style and has great reviews. You want to know that one frame is better at this and one is better at that and one does a lot pretty good but nothing great stuff before you buy. You don't want to end up with a bike you don't like after putting in all the money effort.
John