Just Between Friends is a consignment sale...franchise? As I understand it, someone locally pays a fee to host the sale. In my area (Oklahoma City, Oklahoma) there are two a year (spring and fall). Anyone can sign up and sell their used kid and maternity items- toys, clothes, room decor, basically anything kid and pregnancy related. The seller gets most of the money but the host gets a percentage. Not sure if this exists outside the U.S.
The website explains how the sales work, where they are, and are the way you sign up to sell things. I've never heard of them selling anything online
but it would be cool if they started.
The sales can be a good place to look for ponies, but it's tough to get in early enough- if you volunteer to work the sale (as a cashier or stocker, etc) you get to shop early, and those people usually get a lot of the good stuff. Consigners also get to shop early, but after the volunteers. I've shopped and consigned and found G3s, but never G1s.