Exterminators?

how much does an exterminator usually cost. we have a bee hive under our siding on our house and we have sprayed up there, we have caulked the hole we have done everything but nothing works. both of my parents arent willing to call an exterminator because they think it is expensive. even though my mom is severly allergic to bee stings. so how much does it cost normally to hire an exterminator. i am sick of the bees. we cant shut our air off because if it warms up in here they come into the house. so how much does it normally cost