I feel like if you are running a miner, get both a USB and a miner like an antminer s-1 from what phil said.
The whole reason behind this is, you can show BFGminer or cgminer in action processing information on the USB.
And you can show larger physical hardware, and what ASICs have grown into. From small USBs to larger devices that are becoming more efficient. Also you will get roughly .0004 bitcoin per day to use and play around with if people are interested.
Then point these devices at a pool like
kano.is, and watch over time accumulating some small increments of bitcoin (assuming you run the equipment for a week or so).
Or use a CPU or GPU to mine which is completely outdated and will produce almost nothing to use or play with.
Guide to installing BFGminer on a raspberry pi:
http://computers.tutsplus.com/tutorials/how-to-create-a-raspberry-pi-bitcoin-miner--cms-20353This was the tutorial I used to setup my little lottery miner that has run for months at a time.
Place to store your Bitcoins (Unless you want to download a full client of 60GB):
https://www.coinbase.com/The only reason I recommend this site is because they are American based, and you would not have to setup a full node. The downside is they will ban your account if you deposit to bitcoin gambling wallets.
Then mine to your coinbase wallet address on kano.is.
If you do a raspberrypi, this will be your command:
./bfgminer -o stratum+tcp://stratum.kano.is:3333 -O (coinbase wallet address) -S all