You'll probably find the best prices/selection online, but you should still go to the biggest gun store nearby. Staff there will walk you through the process, give you advice, and you can actually hold any gun you want to see how it fits your hand. Who knows? You might find something you like even better (although being a 1911 fan myself I find it hard to believe

).
For 1911s specifically, this is also a great forum:
http://forums.1911forum.com/
As for what to buy, there are about a gazillion different variations of 1911s in any number of configurations/caliber/quality levels. If you're dead set on a Colt-branded 1911 your options will be fairly limited and on the expensive side, but you'll get a quality firearm that'l last a lifetime in return. Beyond that, only way to get an idea of what you want is to know what you want the gun for and start looking. Here are a few of the more common options, listed roughly from least expensive to most expensive. Costs range from sub-$500 to around $1800 depending on model, note that brands often have a range of costs, some generally more expensive brands do have cheaper options. This list is not exhaustive.
https://us.armscor.com/products/
http://www.americantactical.us/8/catalog.html
http://www.ruger.com/products/sr1911/models.html
http://www.springfield-armory.com/1911-series/ (My personal favorite

)
http://www.smith-wesson.com/webapp/...4_750001_750051_757754_-1_757752_757751_image
http://www.kimberamerica.com/1911
http://www.sigsauer.com/CatalogProductList/pistols-1911.aspx
http://www.sigsauer.com/CatalogProductList/pistols-1911-traditional-models.aspx
http://www.colt.com/Catalog/Pistols.aspx
http://cz-usa.com/product-category/dan-wesson-2/
There are also many high-end custom 1911 manufacturers that will charge you $2000-$5000 for about the best-made gun you could possibly buy, but I certainly wouldn't recommend them for a first gun even if you have the money. Go to them when you want to splurge (there's VERY little a $3000 1911 can do that a $500 one can't) and know exactly what you want.
You'll note that you cannot buy direct from the manufacturer. This is US federal law, which requires that all new guns be transferred through an FFL (Federal Firearms License) holder, aka a gun store for delivery. You can buy online, but the firearm must be shipped to a local FFL holder and then transferred to you after the background check, which will add about $20 in processing fees. In many states (but not all) you can buy from a private individual without restriction, other states require a background check anyway and still others restrict private sales altogether. Google your local laws, breaking any gun law is usually considered a felony. Safe bet is to go through a gun dealer.
As for where to buy, there's the afore-mentioned local gun store(s), but beyond that the most popular options are:
www.gunbroker.com
The eBay of guns, but a lot of gun stores post some of their inventory online. Look for sellers with good reviews and an FFL badge on their wares.
http://www.galleryofguns.com/Genie/Default.aspx
The Amazon of guns, but many models are often out of stock and sell out quickly when restocked.
http://www.budsgunshop.com/catalog/index.php
Good selection and prices but has had some shady customer service issues in the past.
Beyond them there's a multitude of dealers who post their stuff online, just google "buy *insert model here* online" and any number of results will pop up. Do your homework though, some are more reputable than others.