Beginning an art collection is a wonderful experience. You can explore the realm of art in a variety of ways, but having real, original artwork created by the artist, touched with their very hands is a very satisfying thing.
Prints and book collections are a very inexpensive way to get started. I'll start by using a classical cartoonist as an example:
His name is Vaughn Bod and he was a very popular cartoonist of the silver age of comics. He sold a lot of single-page work, and influenced many different cartoonists of that era.
You can buy books of Bod's art from various retailers on the Internet. They can be found even more inexpensively at used bookstores online such as www.powells.com (Also known as Powell's city of books should you live in the Rose City).
From there, you may decide that you would like to pursue some of the publications that he published in. In his case, he published in Cavalier Magazine, Heavy Metal, and the now defunct Epic Illustrated, to name a few. These, again, are inexpensive ways to add to your collection.
After that, you may wish to look at some other influences in his life, for example his son, Mark Bod, who has taken up his father's mantle with a similar art style. Just by Googling Bod will find you a plethora of resources and collectables.
Doing further research on your artist of choice, you can then start to follow his career, and would learn that his art style was a heavy influence on a director by the name of Ralph Batski. Batski directed an interesting film called "Wizards" which has many hallmarks of Bod's art structure in it.
Finally, once you have done your research, perhaps joined various online forums with people with similar tastes, you're ready to step up your collection a notch, and get some original art.
Be warned, here, though, there are issues with forgery, digital duplication, and things of that nature. The phrase Caveat Emptor (let the buyer beware) is critical here.
I have, personally, successfully purchased older art on EBay, for example. It's not my first choice for buying art, but if you look at a seller's reputation, and the feedback comments, you'll probably be able to get a good deal. Sniping software is your special friend, should you choose to go that route.
In perusing cartoonist style works, using the given example, comic book conventions, especially ones that have older art collectors, are also an excellent source for original artwork by your favorite artist.
Collecting art can be a very enjoyable pastime, and encountering other collectors in a live, face-to-face environment can be very exciting as well, to meet people to swap stories, artwork, and information with. There's not much better for the collector to see some small bit of memorabilia and be able to get it for a good deal at a convention.
Enjoy your collection, display it proudly, and happy hunting.