The responses on my Reddit thread should answer this question:
http://www.reddit.com/r/BitcoinMarkets/comments/25dy7l/streaming_market_data_for_bitstamp_coinbase_btce/It would be about $100 per month to support just you and ~$300-$600 for everyone. PubNub gets pricey with this kind of message volume....I just started a conversation with them to negotiate a volume discount. This is my first month not using a free demo account with them so I am having some difficulty nailing down a solid number for their costs.
The only additional cost for turning on data per exchange is the additional message costs. So I really need to figure out what their volume discount will be.
Will you walk me through how to host a websocket for bitfinex on a machine hosted in a datacenter. I am familiar with ws4py and java programming.