No additional charge for HD locals if you already subscribe to your local channels. They are opened to you when you connect your HD box. HOWEVER, the problem is that your HD locals (LIL) may not be on any of the satellites you are looking at today. While some are at 119 and or 110, a great many of them are at 129 or 61.5. So, even though there is no additional charge to get your HD LIL's, you probably can't receive them today because you aren't looking at the necessary satellite. What sats do you get today, or at least tell us if you only have a Dish 500, for example, and what city and state are you located to help us tell you where your HD LIL's are located.
Also, if you subscribe to HBO or Showtime, a few of those HD channels are at the 110 locations and will also be opened for you to view.
However, Dish no longer opens up any of the other very few HD channels at the 110 location for viewing unless you subscribe to HD, which is a $10 per month charge and you will get all the HD equivalents of your SD package. Of course, the vast majority of these channels are at 129 or other satellites, so you would not be getting your full $10 worth of programming.
So, odds are you will not get your HD LIL because they are at 129 or 61.5, but you could get HBO East and Showtime East if you subscribe to those premiums, but nothing else, if you are not looking at 129 or 61.5.
So, you may really want to consider upgrading to HD and they will do a complete install with new dish, etc. so that you can get all the HD you are entitled to. If you are a DYI person and can handle sat installs, then people on this board can help you do that. But it will cost at least a little bit of money if you DYI it. Good luck.