Hi Michelle,
I agree with the others - $300 is way to much in anybody's money, they should be giving him to you, but $50 would be top dollar.
I have reared a blind calf and he did very well but you do have to go that extra mile and ensure that wherever they are put is 100% safe - no gullys, swamps, creeks or ravines. They can smell water so getting water from the trough isn't a problem although I often found mine with his two front legs in the trough.

They don't need to see to graze and find the right grass, they do that by smell as well. They enjoy having a paddock mate and mine developed a symbiotic relationship with a pet wether and a hen!!!
He will learn to recognise your voice and commands and will walk to you and if he's anything like mine, will stop just in front of you at the point when you think he is going to trample over the top of you. There is no doubt that their sense of hearing and smell develops to compensate for the lack of sight.
But you do have to think about what your going to do with him in the longer term if you do opt to take him on. If you want to take him on with the thought that he could become a pet, that's fine but if your looking at disposing of him, you may find that rather hard as you will probably spend a bit more time on him than you would a sighted animal. The emotional side of it is up to you, the practical side is that there is no reason whatsoever that he shouldn't do well.
Cheers,
Ronnie