I just found this script, here is a summary of what it does

iScripts EasyCreate is an online web site building tool that can be hosted on your server to provide online web site building services to your clients. It can be an independent business or part of your current website. EasyCreate is easily customizable - incorporating your logo, marketing messages, custom support links and branding information on the application interface. Since the application is hosted on your server, you have complete control over the working of the site. Your clients can select from pre-existing professional layouts to create great looking websites. It is a perfect addition for web hosts, web designers, ISPs and virtual communities. In addition, it supports payments through Paypal, 2Checkout, LinkPoint, Authorize.net and Google Checkout.

I am interested in getting this or something similar, are there any free or cheaper alternatives or will this script get me the best bang for my buck? :)

How easy is it for a customer to install the site to their account? Does this script do the uploading for them or will they have to do that? how easy is it to use?

Thank you!
Markus

Or would the RVSiteBuilder be a better solution?

I would checkout www.soholaunch.com. I am looking at it for myself.