I'm more likely to become a loyal customer of a company who is confident in their product and will allow me to try it at no cost. If the company suggests I purchase a sample I usually don't waste my money.
The picture is what I've received so far this month.
Many companies will either give you free samples or a coupon to try their product. Take a look at a post over at ToughNickel.com for information on what to ask for and whom to contact.
Take a look at The $39 Experiment for more ideas. The $39 is for purchasing stamps which there is no need to do if you contact the company online.