My Experience doing online training
I have done a couple of course from two different providers.
The first one required payment and then someone at that end to 'turn on' the exam. I rang the number but nothing for a couple of days. I did get through in the end it but it was a touch frustrating 
. That was a while ago but, looking at there system, I don't think it has changed in all that time.
More recently I did the Avstar Solutions course (based on recommendations here 
). Apart from being a better course (content wise) it was seamless in that payment was instant and allowed me straight in. I had some trouble with my computer (yeah... they make our lives 'easier') and sent them an email (not expecting to hear back for a day or so as it was late on a Friday) then 10 minutes later I got a call from John! He helped me sort out my browser issue and I got it all done then and there.
Nothing beats good service in my book.
I think most courses are basically a similar price. I also think they are all open book but not certain on that (I know the Avstar Solutions one is).