Thanks to those who put me on to this website. I did not know it existed. Seems like some really nice horses are represented there. Still have not located the right A/O horse, but have gotten close through this site. Seems like fewer and fewer show barns are listing horses for sale on their websites anymore, so if you know of other websites like Exchange, I would appreciate knowing about them.
Bigeq.com… Exchange is definitely the best though, IMO. Have you asked your trainer? Sometimes the best finds are word of mouth. Also go to a show and ask around. There are always horses for sale. You could also look on FB at region specific groups. I know we have one in texas called Texas Sporthorse Market that gets a fair amount of traffic with horses at all levels.
The Exchange has the highest quality horses and bigeq.com is a runner up. Once you hit the ~80k mark, the vast majority of horses will not be put online. If you’re looking for an established AO horse, a trainer with plenty of connections is the way to go.
Amber is awesome at what she does - if your pony does well or has some good pics or videos at a show - it is up on social media very quickly - not just her website. Highly recommend 
