Make sure that you order only the required credentials about the prospects. For instance, if don't wish to use e-mail for your company's marketing campaign, you should make it clear at the time of placing the order. Every bit of information costs some money; therefore, ensure that your list has only the desired fields.
When you price toward the upper end of what your market will bear, you can do more creative things with your marketing to try to attract more mailing list customers. Your additional revenue covers the costs. You can spend more money to attract your customers and still make better profits, because you were more aggressive with your marketing and ended up with more customers. More customers equals more chances for repeat business or sustainable long-term growth.
That's an important point to keep in mind -- so always think about what you can do to charge more. Maybe you can bundle several products mailing list and services together to create a bigger package that you can price higher, so your average ticket price goes up. Do all you can to increase the size of every order that comes to you; that may be the most effective strategy for making more money with direct mail.