If you are just starting out in your business, or you need a separate business card to promote something, you can get coupons for all kinds of printing. Online printing shops are really easy to use. You can upload your own design, or use one of the templates they provide.
Whenever I use an online print shop, I always google "coupons *online store*". For example, the last time I used a popular site called Vistaprint.com, I googled "coupons Vistaprint" and tons of sites came up with recent online coupon codes with information on how recently they worked for someone. Everything from business cards, to postcards and greeting cards have special offer coupons.
Last month I needed a quick card for a trade show I was going to, and I wanted to make a special offer on the card. I used a coupon code and got 100 cards for $3.99 plus shipping. It worked great!
You don't have to spend hours and hours on how your cards should look. Just make sure they are colorful and have all of your contact information on them. I also add some info on the back about my training classes or any special offers I'm doing at the moment.
Business cards are the cheapest way you can go for printed advertising and usually you combine them with the personal touch of introducing yourself with them. You can also have various cards for various activities that you are doing. When they are this cheap, why not?