I believe it to be an important part of relationship building to offer free quality content to your subscribers

Sure you want to train them to invest and spend money but this wont be accomplished usually without building that trust and letting them know you are someone that a) they should listen to and b) that you can help them.

They can be on any number of 100's of lists that can send them sales emails but if your mixing that with free content that you have created to help them then you will do better IMO

Hope that helps

Dean