How much would it cost to get my dog a haircut?

I only have $20, is that enough? I have a cocker spaniel by the way & she just ran outside in the mud & rain & her hair is kinda long so she looks gross! My mom won't let me give her a bath inside & I really want to get her hair cut short, she already has her shots. Do you think they'd judge me for bringing her in all muddy & wet at the pet grooming place?