Every new feature they add just makes sense – their online store and the membership area being two good examples. Their content management system is also laid out to support rather large websites as we know of Weebly websites that easily count more than 150 pages. Best of all, you’re not constrained by any storage or bandwidth limits in their paid plans.
The basic plan is free, but is extremely limited. Their personal plan starts with $4 per month billed annually and includes a custom domain. Premium plan costs $8.25 per month billed annually and it gives you the ability to monetize your site and advanced design customization. Business plan costs $24.92 per month billed annually, and it gives you the ability to have Ecommerce and custom plugins.
While the the best of them offer surprising amounts of flexibility, they also impose stringent enough restrictions to page design that you shouldn't be able to create a really bad looking site using one of these services. Typically you can get a Mysite.servicename.com style-url with no commerce abilities for free from one of these services; you have to pay extra for a better URL and the ability to sell. One issue to consider is that if you eventually outgrow one of these services, it can be hard to export your site to a full scale advanced web hosting like Dreamhost or Hostgator. If you know that's where you are eventually going, it may be better to skip the sitebuilder step.