I Found Little White Worms In My Dogs Poop Today, I Need To Deworm Him Asap.. Is It Expensive?

i have two dogs and im pretty sure they both have it since they are always together… they have had all of the symptoms (diarhea, dull coat, little appetite, coughing) I really freak out when my dogs are sick so I want them dewormed immediately. Is it expensive? I know i need to supply stool samples but how much does all of this cost??
btw they have had symptoms for about a wk.