well, these days there is famous bot been cracked, Ibot ..so you don't need to buy it . It can kill NPCs and collect boxes without your control, you just adjust the options you want and leave it works alone. One thing more to mention, there is no save bot , which mean you may get banned from DO at anytime,there are several level of ban : on the first level captcha images appear when you try to collect boxes ( to prevent bots from auto collect ), and the last level is to get permanent ban that means you can't use that account anymore. But I'm using that bot since +14 days for more than 20 hours every day and i'm not banned yet ( I only to collect boxes ).
you can download ibot from

and the crack from thread in this forum ""[SAMMELTHREAD] Ibot Crack and License"
I'm a new user.. so i'm not sure from everything i said , i told you what i know