What I should I do to maintain a dog's good scent?

I am fostering a shar-pei-german shepherd dog mix, medium-sized and house-trained. Her coat is very short and not thick. The thing is after I take her out, she would smell YUCKY! at the end of the day. I bathe her once a week. I don't like to bathe her daily because she will lose her coat"s natural oil. So what should I do to let her smell good every day? Is there a cheap perfume for a dog?