Well I've had a Pi for a while, and got given a USB Erupter by my mate (mentioned below) to try mining out, but apart from that nope.
Im only looking at this as a hobby, and it would be cool to have something that would pay for a bit of my rent without really having to do much work

There is a possibility I can get mates rates on a BF Jalapeno (4.5GH/s) and could probably get it up and running within a few days.
What are your thoughts, worth trying at the right price? Or is there really no point unless I'm getting into the 100 GH/s territory?
Thanks
Yes it's quite pointless right now to mine unless you're in the 100gh/s territory. Here's a tip my friend, you can mine in some new pools that don't have much people in them(example:p00l.co). with one block erupted usb you can mine way more that what you could mine in a full pool (example: slush) but will take longer times and there's no guarantee that you will make more but I'm making 0.002BTC per block with my 180mh/s graphics card.