DeWalt also has a ceiling price on repairs for any of their tools. You should call up the service center near you (or any one, really) and give them the model number and type (it's on the label) of your drill. With that info they can look up the motor part number and give you a price. More than likely they'll have the motor in stock. Then ask how much a "max repair" is and see if it makes sense to have them do it for you. "Max repair" means just that - they'll replace anything and everything that is bad. You might want to get a new set of brushes, too. They are pretty cheap and since they are a wear part you might as well replace them at the same time.
If you go the max repair route, you might want to "accidentally" crack the case near the trigger before you take it in. Ask them to replace the clamshell housing and the motor. Makes it look just like new!
Usually the motor is about $60-$70 and a max repair is about $30 more. Total cost on the max repair will be about 50% of what the tool retails for.
Don't tell them I told you that.