There are some really great deals to be had on business cards.
Flyers are single page (normally A5) designs and don't have much about them to cause the client to hold on to them.
I have personally found that producing my own leaflets has had the best result. Initially I prepared a tri fold leaflet using Microsoft publisher and I used a 120g paper for printing. This achieved a quality feel to it. I was able to add my contact details (as you would on a business card), but also an overview of my work and skills. The leaflet can be produced in short runs, be updated often and have photos, explanations etc about you and your products. This has to be an improvement on a business card which only contains your contact details and puts the emphasis on the client to go and look you up to see what you do etc.
Recently I began to use A6 card blanks as the basis and this style has gone down very well. The product looks quality, gives an overview of your services and the client is more likely to keep your card or pass it on. I have had an awful lot of feedback through the cards. Because they say things such as "Karen gives talks to local interest groups" I've been contacted by people who have had the card passed on to them. I have had people give my card to friends who are planning weddings, People who want beading lessons etc. It's been the best publicity method I've tried.