Truthfully it could go either way to me. It might be a below average super, or an above average pastel.
If he has no paperwork, no receipt and won't even let you see the snake before you buy it, now that sounds shady.
If that were a regular pastel who held it's color like that at 1000+ grams, to many it would be worth the $400-500, even if it is male. If that is a super, it's not nearly as blushed out as most people like their supers, and would not be worth that price to most. So it could go either way. However, anyone who wants you to buy an animal or anything else sight unseen, that is a person to avoid dealing with.
Best to wait for a really nice hatchling from someone who'll let you see and hold the baby so you know what you are getting.
Gale