There's 2 sides to the botted accounts story.
1. There are people who are using bots that are detected. They quickly bot their accounts from 1 to 30 within a week and next banwave their bots are easily banned. This is what happens to most people, and that's why 'botted' accounts got their bad name.
2. There are people who use their own created bot, that takes quite alot longer but doesn't get banned wave after wave. These accounts are usually safe for the rest of your league-lifetime.
It's all about how you bot your accounts. There's obvious ways which Riot can easily detect by just checking a few match histories or even use their anti-cheat to detect injection-based bots (Which most are saying that they're not detected, but hey.. we know better right?)
Just be sure to check from whom you are buying accounts, because there's all kind of types out there. Those handleveled accounts are mostly cracked accounts which are basicly stolen because people were stupid enough to have their username the same as their password.. which obviously would be safe from banwaves, but if you have the original email you registered the account on you can ALWAYS get it back.
Kind of a long post, but I hope this makes your choice easier
