yes, the horse market sucks in Wi too. We got an exellent mare for 100, though we had no proof that she rode, just word of mouth. She rides, and is nearly bombproof.
We have been selling some our stock who are pretty well broke for 500-700. Even our all blind mare went for 500..
I actually think that 400 is low for your gelding, even if the market is bad.
He is a young horse, has training, and is a good size. I honestly think that you should ask for 700 or so, and maybe accept less. Even if he does have a blind eye it doesnt seem to bother him. If you can, get a video of him riding with some obsticles, to show that he doesnt spook or startle at things, if you don't have a camera that can do video, try getting a few pictures of him in action.
EDIT:
I agree with the above poster, about how people just getting started in horses look for cheap horses. Be careful with these people, watch them as they handle him. Ask them questions like how they would get a horse from the pasture if the horse won't come. We have found this is a great question to ask to find out who knows horses and how well they are treated - No, chasing after them with a whip is not the way... goodbye sir.
Although he sounds great, I do think because of his blind eye that people that have owned a horse prior would be beter equipt to have a horse that has a little handicap.