Honestly if she's broke, sweet and safe and a relatively easy keeper, she's worth $1500.- 1800 easily.
In that price range your concerns should primarily be temperment and training, rather than conformation.
That said, based on this single photo, hers.... isn't good.
Her hind leg is very, very, very straight - pretty much the text book photo for post legged. AND her hock is set very low on that leg, but that may partially be an optical illusion because there appears to be no joint between her hip and hock.
Her croup is higher than her with, and falls off at a steep angle.
Her pasterns are on the short and upright side for my taste.
BUT...all that said: Can she do the job you want her to do within the price range you've set? Is there a better horse with better conformation out there in your price range that you like as well? Those are the key questions.
If you do like her, do have a pre-purchase, and do be present to ask the vet questions about her conformation, her soundness and what you would need to be mindful of if you do buy her.
For instance, post legged horses are prone to stifle problems, and do better if kept moderately fit.
