Yes I can buy it, but then you need to include hardware installation price and hosting price.
And if the Amazon computer hosting my vm dies, the system will just boot up on a new computer and restart the vm, without me even knowing it. With the dell I would have next day business service aka far to much down time.
The reason the company I work for uses vms(Not from amazon however) is that if there are hardware problems we just reboot, and if there are to many problems with our host, all we have to do is a dns change, a scp, and a database copy(Or restore from backup) and then we can be online in a new data center.
I would however be cautious with a big database server at amazon, because I don't think their io performance is that good, and than is the thing a huge database server really need.