With personalized email marketing you can offer a different incentive based on the investor's income level, or other criteria. (So you don't have to give away an annual membership to everyone to gain their business.)

Obtain a segmented email list based on a few criteria (occupation, income level, etc.) and use that in conjunction with a PURL or personal website using personalized graphics and offers based on the prospect's personal information. Prospects visit the PURL, voluntarily input valuable information, and take advantage of your offer.

This serves several purposes: 1) You increase response rates by marketing to a targeted group 2) When the prospect answers your questions on the PURL you learn about their wants and needs and can then personalize future communication 3) You're also building a mailing list. This is an inexpensive way to increase your market reach and ROI.

Variable Thinking, http://www.variablethinking.com is the best company I know for this service.