I figured I'd just put my opinion in, although its not 100% necessary as people have all voiced some excellent points and I know you have a lot to think about now... This is more my personal experience.
I had taken a few year hiatus from riding and owning horses (well not riding 100% as I still would ride every now and then but no competing, no lessons, etc) and then when I got back into it I ended up purchasing a horse that to be completely honest I had no business buying! He was an unbroke 3 y/o that was just to the point where he was ready to go undersaddle... As I loved his ground manners and he seemed like a big angel (and he was in my price range....) I ended up bringing him home. NOT the horse I thought he was and it was a tough journey. I ended up investing way more money than I had ever thought as he was terrifying and couldn't be started by anyone I knew, so I had to hire someone to start him for me... and ride him for a few months until it was safe for anyone else to get on.....
Long story short, I know your horse is not the same situation here, but be careful with your choice and definitely think into the future. Its a good plan to work with a trainer but consider all costs and what you will be missing out on while your waiting for you and your horse to mesh. I have been very patient with my horses training and I'm glad that I have and how far he has come is amazing, but theres many times I wished I could partake in stuff over the years that we couldn't due to us not being ready. Looking back I did not make a good choice and should have continued looking for the perfect match instead of falling in love with my guy. It would have been a lot easier on everyone, but at this point I wouldnt trade him for the world.
Good luck with your decision, she looks like a great horse, but there are many great horses out there so just be sure that you are comfortable with whatever you decide!