If it's going to be your first 1911, I would not build one. I'd buy a good, reliable 1911, shoot it a lot, learn how it works, and then decide what about it (if anything) you would like to change...and then decide whether you would rather modify the one you own or buy a better one. Or do both....in time
There are lots of 1911s out there, starting around $400 and going (way) up from there.
Let me try to draw an analogy: If you wanted to buy your first Harley, you could find a beat up, crappy Sportster on CraigsList for $1800...or you can buy an Arlen Ness custom for $45,000+. And there are about a million choices in between. 1911s are similar in several respects--the basic design has been around a long time...they are both well-loved by their supporters and bashed by their detractors. You can easily overpay if you don't know what you are looking at. If your first experience is a positive one, you may very well enjoy a lifelong passion....and vice versa
The fact that 1911s have been around forever means that there is a huge aftermarket parts and accessories selection out there. On the flip side, this encourages lots of people who know very little about their 1911 to attempt to "customize" them. For that reason, buying a used 1911 for your first is probably not a good idea; although it could potentially allow you to save a good bit of money, you can just as easily buy someone else's headache...esp if you don't know what you are looking at.
If you have several hours, the following thread may make your initial decision process a lot easier...and save you a lot of money and heartache in the long run. Most of us do not have the wherewithal to buy "one of each" (to say nothing of the ammo!) and then own and shoot them all. Fortunately, this guy did, and does, and has done much of the work for us:
http://www.1911addicts.com/showthread.php?511-Buyer-s-guide-for-all-you-1911-addicts
There are many great 1911s, but none are perfect, although many 1911 owners would debate that statement.
The real question is...which one is perfect for you, at this stage of your 1911 journey?
The above guide will also allow you to start with a dollar figure in mind, and then allow you several good options within that price range.
If you are like many of us, your first 1911 will not be your last. There is a reason the design has been around over 100 years, and is more popular today than at any time in its history. Check that--lots of reasons.
1911s are available in 3", 4", 4 1/4", 5" and 6" barrel lengths.
1911s are available in 9mm, .38 Super, .40S&W, 10mm, .45acp chamberings (also .400 CorBon, .460 Rowland, .50GI and others, but I am starting with the more common cartridges).
1911s are available with frames made from the traditional carbon steel as well as stainless steel, aluminum alloy and Scandium (and I believe there may be a polymer frame or two out there somewhere).
There are probably 40+ manufacturers out there who sell a 1911, and many of them sell a whole bunch of different ones.
All of this adds up to untold kazillions of possible combinations.
To attempt to answer your question directly (and bear in mind, this is only my opinion...)
--Shoot several, if you can. If your range rents handguns, that is a good place to start.
--Decide upon a cartridge --.45 acp is the most common, and hard to go wrong with. It will also afford you the largest number of choices/options. (If you have numerous handguns and are an experienced handloader, you may choose to disregard this advice.)
--Decide upon a barrel length--the standard 5" is a good starting point, esp. if it is your first 1911, and esp. if it is to be used for range/HD use. If you later decide to carry a 1911, you have a reason to research further, and perhaps buy another
--Decide upon a frame material--for the same reasons stated above, the steel "original" is a good starting point.
--Decide on a manufacturer...or at least narrow it down to three or so that you will accept if the price is right.
Here is where it gets tricky. Everyone has their favorite. If you are going to buy new, (IMHO) a manufacturer with a good reputation for quality AND
AN IMPECCABLE REPUTATION FOR CUSTOMER SERVICE/WARRANTY should rank very high. I have owned many a 1911, most of them bought used, and had only a few that needed serious work.
My experience does not mirror that of some...for example, I have had three Colts and will likely never own another.
The following manufacturers all have exceptional reputations for Customer service (CS), and I would recommend each without hesitation, based both on my experience and upon their reputations in the industry:
I have owned three Springfield 1911s, and while their initial quality was disappointing, Springfield did everything they could to make the guns right. For that reason, I have no problem recommending a Springfield 1911--new or used.
I have owned two S&W 1911s (one new/one used) and neither has needed attention, but S&W has an outstanding reputation for CS. I have owned other S&Ws that needed a trip back, and S&W's CS was exemplary.
I have not owned a Ruger 1911, but one is on my list. I have owned a number of other Rugers...one of which had to go back. Again, exemplary CS.
Each of these manufacturers will pay shipping both ways (which is a significant consideration), and will fix a gun even if you are not the original owner. Now if you or the prior owner butchered it...probably a different story, but at least in the case of S&W, they have even been very gracious in some extreme cases.
Each of these three also build several 1911s that offer (IMHO) quality/features/value well above their prices.
Okay, I've been pretty long-winded, and I apologize for that. But many people make a poor choice, then regret it, and then bash either the manufacturer or 1911s in general for the rest of their lives.
Good luck with whatever you decide, and please let us know what you buy and how you like it.