I wish I could give you the perfect answer-- we are using Infusionsoft + CustomerHub, which is NOT the best solution given they don't have a forum feature-- we have had to tack on "Tender" which is built as a support ticket/help desk engine and we've had to modify it quite a bit. I think it's ridiculous that CustomerHub doesn't have a forum given they are a membership site platform--!? Anyway, I can speak to Infusionsoft-- yes, it is expensive and yes, it is complex, but I am happy with their ability to handle VOLUME and their ability to customize and refine to infinite possibilities. There is a lot of power in that and it's built for growth and seems very sustainable. I have had a membership site for 9 years, and believe me, you don't want to move your entire platform when it becomes obsolete-- that is a huge job. You do need some assistance setting it up, but after that you can maintain on your own. I also love the way I can run multiple businesses/income streams all through one Infusionsoft account. That is valuable too. Hope this helps.

Check out combining Member Mouse and Active Campaign.

Two issues in this question. Building the site, which is going to be very expensive. The second part getting customers, you have to have a plan for each. Remember most people have plenty of internet power, software and sites, and are not open to set up with another system.