stroller for sale

Last year we bought this stroller: http://www.babytrend.com/sit_n_stand_dx/SS74740.html It's a stroller with a seat for a small child and a sitting platform for a larger child. Our thinking was that by the time Cicily had a smaller sibling this year, she'd be steady enough to sit on the platform of this stroller. Unfortunately she is not more steady and still cannot walk on her own. So, I asked a couple of my friends who have also had non-walkers and a baby, and they said a small double jogging stroller is a must! For us to get into doctors offices, therapy offices, etc. without making more of a commotion than we usually do, we'd like to buy one of these: http://www.philandteds.com/upload/index.php/push/46 A Phil and Ted's double stroller that Cis could sit in for years to come. (Never, ever thought I'd spend $500 on a stroller!)

If any of you out there know of someone who would like a Sit and Stand stroller, we'd love to sell them ours! It's been used a total of 3 times, so it's pretty much new. Thanks