Most likely this horse has been tied to a post to try to "break it" from being head shy. These very old and barbaric methods of breaking a horses will often cause them to be afraid of people, very head shy for the rest of their lives. It is sad.
You can really help this horse! We had a horse very much like this and she is now showing very well. But even today we are very gentle and careful around her head.
You will need to desensitize her to any movement or touching anywhere on her head. I'm sure you know the process; gentle handling, noise, touch on her nose and slowly moving to her poll and ears. This process can take A YEAR OR MORE. But you can do it. Also, in our case and many I've seen, such a horse will always be head shy, but your goal will be to get him usable and handleable.
Confidence and trust will need to be built between you two over time, perhaps even before you begin on this problem. However you have to be able to halter him in order to do basic training etc.
Sounds like you are the right person for him at this point in his life and you will be good for him.
Thanks!!
First of all, I would rec. a prepurchase exam on the horse by an Equine vet before buying ANY horse, regardless of purchase price. You just want to make sure you are not getting into more than you expect and it will be worth the money. As far as being head shy, I agree with Dr Jim that it can be done, but will take a lot of time and continual reinforcement. Search Google for the Equine Behavior service at the University of Pennsylvania and read articles written by Dr Sue McDonnell on the subject as she is the expert in this area and she has articles that address this issue