OT: I used alpha trade for L2. I was told that it was the cheapest way to go. After doing some searching I agree that it is probably the cheapest. It can cost anywhere from $20 - $100/month depending on what features you want. I spent about $60/month for all big board, OTCBB and PINK. Great service. I highly recommend.
Edit: Also if you have 25k in your account, usually your broker will have free level 2 since you are a preferred customer. ;)