I personally am not sold on the fader gene. It's probably just a low-contrast albino. I prefer the high-contrast, almost orange albinos so I would pass. But if you really like him, I would offer $250.
If you like it and you trust that the guy is telling the truth then go for it. $300 isn't bad for a breeder size male albino. Just keep in mind that low contrast albinos (which is what I believe this one is) seem to be harder to sell than high contrast albinos