Yes I think it is possible to build a substantial income with SFI within 3-5 years by purchasing a few S-Builder Co-Op Shares each month, especially if you sign up for a Standing Order. You can duplicate yourself by training your Affiliates to do the same. This is the way to go if you have the available finances but not enough time to advertise and promote your business. You have to be available to support and train your PSA's though.