I have a similar project pony so I am really interested in what people have to say.
The market is so bad right now, it is hard to say. In better times I would say $5000 after her canter is solid, goes over small jumps calmly and has show exposure. Right now, probably less. Her conformation is not that stellar for what you are looking to do with her. Not to say her conformation is horrible it is not, but there is nothing about her that jumps out at me and says 'Wow look at that nice _____'.