Hi C.,
You can sell anything for FREE on www.craigslist.com. Make sure you are on the sacramento site, go to for sale - baby and kids. Make sure you create an account before you post your items. You can post anything without creating an account, but then you have no controll over your posting and it expires after 7 days and disappears. If you have an account you can re-post it if it doesn't sell right away. Be sure to include pictures! A lot of people wont even look at the add without pictures. This is an awsome way to sell all of your old kid stuff and other stuff.
An alternative is to take it all to Once Upon A Child and see if they will buy it. They wont give you as much as you could get on your own, but it may be simpler if you are near one of their stores.
Hope this helps.
D.