Marketing Help?

I own a small business. I need to reach people in research labs. What is the best method. Should I go with email campaign, magazine marketing and if so (should that be a general magazine or a scientific one), or what other types of marketing would you suggest. Please let me know you experience with marketing and I am open to all suggestions that don't cost a lot. Also, the people that I am marketing are all over the US and are mainly in large universities