I've published both through a big traditional publisher and through self-publishing. Here are my thoughts on both:
1) Traditional - About your only hope of getting a short story collection published this way is to first make a name for yourself as a writer by getting short stories published in some well known venues. However, this is very difficult, since there are not a huge number of places that publish short stories and they are all overloaded. I've sent out a number of short stories myself and never had any luck. Your chances are slightly better in the mystery or science fiction genres because of a pool of targeted magazines.
Even with a traditional publisher you should be prepared to do most of the publicity and sales work yourself.
As far as an agent, a good agent is worth the commission they charge (10%-15% upon sale) but not easy to get. Never go with any place that charges a flat fee or a reader's fee. If you want to sell on your own, your best bet is to learn how to write good query letters. Writer's Market is still the essential resource for either finding an agent or a publisher, although of course these days you can do most of the same work on the internet --if you know what you're doing.
2) Self Publishing. Beware! There are plenty of vanity presses looking to exploit self-publishers. This is probably only a good route if you are willing and able to do a professional job of editing and producing your manuscript yourself.
If you want to just sell to a few friends, your best bet is a POD such as lulu.com. They only charge per copy printed, and can print as many or as few as you want. The price to the consumer is comparable to the retail price in a bookstore, and the profit to you per book is comparable to a standard royalty. However, you will not be able to sell your books in bookstores because your per book cost will exceed what any bookstore will pay for wholesale.
If you want to print in bulk, don't find a "publisher", find a printer, and be prepared to be your own publisher --which basically means running a small business. I highly recommend the "Self Publisher's Manual" by Dan Poynter if you want to go this route. Based on my experience, expect your baseline costs to run about $10,000 for a minimum-sized run of 3,000 books (i.e. about $3 per copy). You'll still face an uphill battle to get placement in bookstores, and will need to be prepared to sell all your copies through your own marketing and sales efforts.
I published my book "Hero For Christ" ( http://heroforchrist.com ) as a self-publisher two years ago. Since I have desktop publishing experience, I was able to do all the pre-production work myself. I was also lucky to be able to handle the business aspects under the umbrella of my father's graphic arts business. Even with good critical reviews and cover blurbs from some nationally known figures, I was only able to secure placement in local bookstores such as The Book Suite ( http://thebooksuite.com ).
Since publication, I've sold 500 copies and made back just under half of my initial investment. At this pace, I'll sell out my run in six more years for a profit around $20,000. However, nearly all of those sales were direct sales based on public speaking engagements (with a few more coming through strong word of mouth, and just a couple coming through amazon.com or my website). So I've had to learn to be a public speaker as well, just to support the book. Add in the two years it took to write and research the book, and the additional year it took to produce it, and you're looking at a ton of work for a relatively small financial return.
And in fact --a little trade secret --even most authors who are traditionally published make the income they live on from public speaking, not from book sales. For example, my children's book "How the Fisherman Tricked the Genie" ( http://www.kitoba.com/fisherman.html ), which was published through Simon and Schuster, got stellar reviews, was nominated for several awards AND had national placement in bookstores, still only netted me about $8000 during the five years it was in print --which is a very long lifetime for a modern picture book. And that's in a niche that is a lot more saleable than short stories. So, not to be discouraging, but the previous poster is definitely right --don't do this for the money!