Lot's of good advice here. I'll share some more with you if you promise not to use it in my area. I'm in a similar situation to you, living in a town with lots of young girls looking for stylish 'vintage' Mixte or step-through frame road bikes. Having ascertained this I focus almost entirely on flipping this style of bike.
The emphasis is WAY on the condition of the paint/chrome as well as having a decent seat and getting it in good working condition to minimize trips to the bike shop. If you're selling a ladies bike name recognition means very little in my experience. I made my biggest profit on the sale of a Zebra-Kenko Thunder, a no-name bike that had gorgeous paint. What does mean a lot is having it clean and shiny. Adding 'custom' touches like coloured housing, using a paint pen to outline lugs and colour co-ordinating with the bar-tape or grips is key. I use my fiance as a style consultant and on average we clear $200 for bikes we sell.