The Death Penalty

So I was looking through the news and I found what's a been a major topic for a while. The Boston Marathon Bomber, Dzhokhar Tsarnaev, being guilty of all 30 counts he was charged with.
From what little I know it does appear that he did this, so I'm not sad or upset in any shape or form that he was found as such, though again, I don't know very much about the trial. But there are two things that I have found over the last week or so that do both me.
1. One of the charges (if I'm not mistaken), was use of a weapon of mass destruction. Seriously? A homemade bomb now counts as equal among chemical weapons and nukes? Sounds a bit overboard to me. I know a lot of people were hurt, but I'm not sure something I can make with the stuff under my bathroom sink is on par with Fat Man or Little Boy.
2. He might be facing the death penalty. And here we go. Murder is wrong, the vast majority of the people on this planet would agree with that, so can someone tell me why it's allowed when someone is found guilty of murder? You killed someone, a terrible crime that will send you to Hell, so we, the State, are going to murder you. Where's the moral high ground in that? I despise in any way shape or form and no matter what it's name. It's why I am now anti-death penalty, along with anti-abortion, and most importantly and fervently anti-war. I'm consistent, a fact that most people cannot say (i.e. right wings are 'pro-life' but also like the death penalty, while left wings are anti-death penalty and 'pro-choice'. And both have been shown to like war).
Now, with that job out of the way, let's discuss the death penalty. It's been around for a while and more than a few people have faced it, one among them being Jesus of Nazareth, and he died in one of the worst executions styles ever, which was literally synonymous with torture. Over the years we have found out that many of those who have been executed were innocent of the crimes they were charged for. What's worse , they may have been alive to see themselves free if they had not been executed.
My main problem with this is the morality of it, as stated above, but that's only one argument. Death penalty cases mean an automatic appeal in our (US) courts and those can take years. In the most extreme cases, decades. They drain money and give little to nothing in return. The person's already going to rot in prison forever, why does it matter if we sentence them to death? They're effectively dead already.
Overall it all seems stupid. At one point I did support the death penalty, but the more time that goes on, the more I find it ridiculous, not only morally, but economically. We waste money on something that takes away moral superiority over the person we're sentencing. We don't get to say, "You did something horrible and I want to kill you, but I'm better than you, so I won't". Personally I'd like to be able to say that.
With that I bid you all good day. Hopefully I got you all to think on this matter and I eagerly await your replies.