I found some stunning figures on the Marketingcharts.com web site regarding Ecommerce, seriously, I always knew the internet was going to be big, but these numbers are mind-boggling.
Another significant point made in this study is that most consumers shop at the same site, in fact 60% of consumers said they tended to shop at the same site over and over. What this means is the first experience that shoppers have with your site matters, big time, you let them down the first time they will never be back. Nail the first experience, and loyalty seems to be almost built in.
This goes for any “first” on your web site, this goes for your registration pages, sign up forms etc. if you lose people their you have likely lost them. On a related note check out this article I wrote a while ago called What Is Your Sign Up Form Telling People, seriously they can even be fun 
Definitely the first experience dictates future spending. I only have to look at how I act on the internet when spending. What is also interesting is that some companies do their utmost to get my email address and name, which can be off putting, whereas others hardly make any effort at all. James D. Brausch for example does a great deal of his sales via his blog where he has a loyal readership. That’s the only place he tries to get contact info.