Question: Need a makeover for my girlfriend, please help?

 Hello, my girlfriend is a nurse and she was over weight all this time. But recently she worked hard and lost about 12 pounds. Her birthday is next month and as a gift I would like to buy for her 1-2 dresses, 1-2 pretty skirts and blouses. She has a standard look since many years. Most of the time she is in her nurse uniform and other half of the time she is wearing jeans. But I want to help her change her look. I am not very good at shopping for women. Her size would probably be 8 now since she is thin now. She has a wheatish complexion and wears glasses.

I need help in deciding where I can buy fall dresses from? What my budget should be because I don't want to buy anything cheap nor do I want to go out of my way paying hundreds of dollars? Her personal style is she likes floral print. Is floral print just for spring? Besides what are fall colors for dresses? What stores do I go to? What days are best for shopping-discount wise or coupon wise. I would appreciate advice from a lady who is a fashion guru. For security reasons I would not upload my girlfriend's picture but you would get a general idea of her look from the following picture.Thanks.