From your description a quick assessment is in the ballpark of at least $5000 minimum. I am sure you have an idea of what you want your collection to be worth based on what you have put into it all. The only way to get to a true value of the collection would be for each doll, item and outfit set to be individually assessed; and I personally handle only one item per question here.
The best way to have your collection assessed will be through an auction house that has specialty Barbie sales. Most all auction houses will provide the estimate for free if you contact them through their website.
Here are some suggestions for you and their website links:
McMasters Harris Co: http://www.mcmastersharris.com/
Leslie Hindman: http://www.lesliehindman.com/sale/modern-barbie/