I'll be using 8 Erupters with a Rosewill off of Raspbpi, once they get here:) (If only I had bought them when they were at their actual price, not inflated. oh well:)
It'll be interesting to see the difference in numbers, in comparison to GPU mining from a single GTX 670 (max I have gotten is 298kh/s). I'm more interested in the aspect of mining/minting, and the cryptocurrency environment...and see what happens in a few years down the line. I do have a second motive, however, for doing this.
I'm an fault analyst by trade, but I'm actually looking to use this endeavour of teaching myself how to put these together, and creating a workshop in my area for underprivileged kids that are interested in computers. This way, they can see all of the things that they can do, without the latest and greatest hardware. Perhaps give them a bit more interest in coding, programming, whatnot. To see a simple, small board put together and accomplish something, I think, would be very inspiring.
Since I got a way bit off track there:))
Erupters in this market are running at mid 40-60 range (USD), and will net you only around 336 per. It is significantly less expensive than the box alternatives. If you aren't looking to absolutley roflstomp through coin gathering, that would be a good way to get started, and see if it was something that interested you enough to invest more. From there, you can also look into contracting time from someone's rig, or possibly butterflylabs rental program per GH.
With 100 to spend, however, you will not become the next Donald Trump:)