The cheapest I was able to get HBO in Redwood City, California, was $72/month all in - and that was waiting for a bit over a year for their $20/month special. The cost of the Digital Cable was the thing that made it pricey (in addition to the basic cable service).
Given that the only thing I wanted cable for was HBO, that meant I would be paying $72/month for HBO. A little rich. My over/under is probably around $30/month.
The only thing that will keep me away is if the price is a lot more expensive than the $14 a month I a currently paying for HBO.