I'm in the minority, I would much prefer to deal with a rearer than a bolter (or better yet a bolter bucker- cause we all know those are fun).
My main horse, pepper, can be a rearer..although it only ever showed itself when we are out on big group rides and she wanted to GOOOO...and I wont let her, which can make her want to rear:/ I admit though she's pretty non confrontational so a couple times of me jumping down her throat for it, and making her move her feet (usually small circles) she gets the hint. I know she does this though and I wait for it everytime I take her out on a big public ride, and steer clear of the group until I know she has is out of her system. If I knew this before I bought her, I STILL would have bought her as she is a fantastic mare.
Now I admit that in my younger days I did cure a rearer by yanking her backwards (i new it was coming and I wasnt on her back AND I ACTUALLY did end up buying her from my friend)...she NEVER reared again after that..I was young and dumb and wouldnt fathom doing that now, as I find it much easier to head the rearing sucker off before the rearing starts (they tendto get VERY light in the front end before a rear), by switching brain gears and taking their mind off of it with doing something else.
That sucks you got taken, because this mare is FAR from a novice friendly horse. Hopefully you can find someone willing to take her on KNOWING she has this issue.