You of course know that you won't save money over a factory gun, but this is:
A. Fun.
B. A good way to really get to know the 1911.
C. An object you can take pride in having built.
My advice, is to make sure you have at least Volume One of Jerry Kuhnhausen's book "The Colt .45 Automatic: A Shop Manual".
Next, for your first build, don't get "cute".
Stick with building a more or less stock Government Model.
After you learn how to build the gun and learn all the problems involved, then you can either modify it, or build another one with all the custom features.
Its hard enough to figure things out the first time without adding the confusion of trying to do major modifications or install custom features.
For the first time, buy ONLY top quality, brand name parts.
Stay away from the gun show and internet "no name" generic parts.
These are almost always cast, low quality parts that are always out of spec in at least some areas.
This greatly complicates assembly when you're trying to assemble parts that are out of spec and don't fit correctly.
Since each part is incorrect, the tolerances "stack" and make getting an assembly of parts to fit and function correctly very difficult.
Name brand, high quality parts have less variation and go together much easier.
For the first job, stay away from Match parts. These require more fitting, whereas standard parts usually go tighter with little or no fitting.
Once you know your way around the 1911, then you can install Match parts.
If you want a slide and frame tightly fitted, buy them as a set, preferable one that's been pre-mated by the manufacturer. Using a slide from one maker and a frame from another is often troublesome.
Again, buy a quality frame and slide to prevent problems with fitting barrels and other parts that are made to Colt-GI specifications.
Less expensive frames often have holes that are mis-located or even not drilled straight.