If you're creatively inclined, you can make them yourself on your very own computer. I'm in the process of making myself some cards right now. If you have a printer at home, you can go to any office supply store (or Walmart--that's what I did!) and buy Avery blank business cards. They're next to the paper/school supplies and come in 8 1/2 x 11" micro-perforated sheets of 10 for a total of 150. I paid $6 for a package. Then you can use any word processing program like Microsoft Word and look at business card templates (I only have MS Works and mine were listed under the "labels" templates). You pick the template based on the 4-digit number on the package and it creates one for you with spaces the same size as your cards. You can choose to make more than one style of card, or to have the template copy one style of business card to all 10 spaces on a sheet. Then you can either type your information into the space provided, or (if you want them to look nicer) whip something up in Photoshop or another image program before pasting the image into the template. I created a new document in Photoshop the same size as the cards (about 2 x 3.5 in) and used that to design one.
You can print on both sides of the cards if you want to; I used the same logo image that's going to be on my new readings website (a bird) with all my info on one side, and on the back (feel free to steal this idea) I took scanned/borrowed images of my favourite tarot cards and fit them so that each image was slightly smaller than the back of a business card--it's smaller than a tarot card, but with the space for a white border around the edge, it looks exactly like a tarot card. You paste your finished design into the template, put the sheets in your printer, and away you go.
Of course, if you're not creatively inclined, there are places that can print them up for you
Hope this helps.