I am new to Visionaire Studio. So I thought I'd try it out and decided it would work for me, so decided to buy an Indie Licence and that's where the real adventure began! 
I clicked on the "buy now" button in the wiki-page which took me to a "404 page not found".  Bah - no room defined!  So I thought the wiki must be an old site. 
I went back to the starting home screen; clicked on the "licenses" menu on the main site, filled in the order form; clicked on 'paypal' option and then clicked the "checkout" button and then received a "500 Internal Error" and a whole load of cartridge exception errors with server folders not receiving the right parameters. Did I have the wrong payment card in my inventory? I tried the other options with more interesting errors. 
I tried 3 browsers on different machines before giving up!  I am not meant to have it, obviously :-)
But since the above error, I just read on the forum that there is supposed to be a major new version 5.0 coming out in early 2017. So I guess it will be much safer for me to wait until that version is released first, so that I don't take an unecessary risk of incurring a further upgrade charge, maybe?
So the server error probably did me a favour. Here's waiting patiently :-) 
JB
PS: For Ref.
Visionnaire Web Error
500 - An error occured.
Der Objektverweis wurde nicht auf eine Objektinstanz festgelegt.
bei siteface.module.ShopController.checkout(CheckoutObjectFinished checkoutObjectFinished) in G:\Webs\SightView\sitefaceModular\moduleShop\Controller\ShopController.cs:Zeile 933. 
bei lambda_method(Closure , ControllerBase , Object[] ) 
bei System.Web.Mvc.ReflectedActionDescriptor.Execute(ControllerContext controllerContext, IDictionary`2 parameters) 
bei System.Web.Mvc.ControllerActionInvoker.InvokeActionMethod(ControllerContext controllerContext, ActionDescriptor actionDescriptor, IDictionary`2 parameters) 
bei System.Web.Mvc.ControllerActionInvoker.<>c__DisplayClass15.b__12() 
bei System.Web.Mvc.ControllerActionInvoker.InvokeActionMethodFilter(IActionFilter filter, ActionExecutingContext preContext, Func`1 continuation) 
bei System.Web.Mvc.ControllerActionInvoker.InvokeAction(ControllerContext controllerContext, String actionName) 
bei siteface.Default.Page_Load(Object sender, EventArgs e) in G:\Webs\SightView\sitefaceModular\siteface\Default.aspx.cs:Zeile 106.