Check the fine print of your contract. Not all contracts are the same. There may be clauses for waiving of the early-termination fee, plan change fees and installation fees (if any). See if the situation that is leading you to cancel your service falls within the parameters of any of those clauses.
Call customer service and ask for the fee to be waived. Explain your circumstances and see if DISH will make an exception for you if you do not meet any of the conditions that will automatically waive the fee for you. Be polite; it never hurts to ask.
Contact the Better Business Bureau or your state attorney general if you feel that your fee should be waived but has not. You can also contact them if any part of your contract seems unfair or vague. In some cases, they have successfully lobbied on behalf of a consumer to get fees waived by DISH Network.