I sold a LOT of my baby stuff using Craigslist...it's free online advertising by area. You can post items with or without pictures, provide detailed descriptions, set asking price and any set any terms such as cash only or must be able to pick up. The reason I like this so much is, I don't have to drag everything out and HOPE someone takes it. I take a photo, post my ad and wait for someone to e-mail or call for pick-up arrangements. VERY simple. For larger items (bouncer & Exersauser) that were gently used, I would look up the retail price and list the product for 1/2 the retail price or maybe slightly under.
Good luck!