Demy - oh I think my florist can TOTALLY do what you need for your budget!
Her name is Lan and her company is H&L Photography and Flowers. She works out of her house, which means not much overhead...which means cheaper for us! She does really nice work, but she doesn't have a website - only has albums of
her stuff at her house. But you can check out some photos on yelp too. I'm not sure how much she charges to go to Sonoma, as she's in San Jose. Doesn't hurt to ask though!
Here are her yelp reviews: http://www.yelp.com/biz/h-and-l-photography-and-flowers-san-jose. Her email is huonglan_nguyen@yahoo.com
(Please let her know that Christine referred you. :-) )
Also, you may want to check Floral Design Studio in Fremont. I met with her, but decided to go with Lan. Nona's stuff is great and she has been known to work w/in a budget also.