I found a gorgeous one at the Goodwill, actually, for like $15 believe it or not. I don't have many pix of it, but here's the best I have....
I just use it because it looks nice.....lol. We live in a pretty flat area and have no need for breastcollars. As for the different types of breastcollars, here's an excerpt I found online:
"If you are doing any hill work at all on your rides, I strongly recommend a breastcollar for your saddle. They help hold the saddle in place, reduce friction by saddle slippage, and disperse the stress of holding the saddle in place from the cinch.
There are a few types of breastcollars, all of which will do the job if they fit your horse. My favorite is what I call the Backcountry Breaststrap
because it is easy on and easy off. In my experience, it has been the least likely to sore a horse. However, many people like the look of the three piece breastcollars, which come in a number of styles including straight, contoured and a more English styled breastplate with an overcheck strap. Once again, all of these are fine if they fit your horse correctly and do not rub and cause soring."