Yeah Powerbot is by far the best bot I've ever used. You don't really need VIP, I use all the free scripts and they work just fine It depends if you want to run more than 2 bots simultaneously though. If that's the case I'd recommend buying VIP or you won't be allowed to.
There's not only Powerbot though... SIMBA is meant to be fantastic. I've never tried it because I've never really had the time. There's a huge section on Sythe here regarding SIMBA. You should definitely consider looking it up as it's supposed to be un-detectable (from what I've heard) Also lots of people have posted guides and stuff so it'd be fairly easy to learn, I think...
Here's a SIMBA forum if you decide you want to go ahead and learn: http://villavu.com/
Just be careful though, Jagex have announced they're upgrading their Anti-bot, so I'd probably recommend SIMBA anyway as there's less of a chance of you being banned. As well as that because EoC and HTML 5 or something is coming out on RuneScape soon it may fuck up the bot scripts. From what I've heard SIMBA may be able to cope with that a lot better.
Just a couple of things for you to think about
Good luck!