Hi,
I have one on my site.
Sales have increased but I couldn't say it was purly down to that - trafic has also increased and sales / visitor is still about the same.
What it did do was show me places on my site which were potential security issues - and how to fix them!
Most importantly they showed me where my host had holes in their server configuration.
which is how I ended up here - trying to find a new host as they won't close them.
I'm looking for a host who is certified by scanalert to be hacker safe cos no matter how much work i put into my site if the host isn't dong their part I'm not going to get anywere!
as to the cost - what I found was that the list price is quite a lot but hosts that are certified usually get you a discount - one host offered 70% off - more than covered the incresed cost of
web hosting!
Hope that helps
Thanks
Steve