Maybe slightly OT - $ share in MTT winnings

[A_PLUS]

$500-1000 feels right to me.

If you were getting Staked, a 50/50 deal would be reasonable. Since, he went beyond that, and gave you an above average stack with 85% of the field gone, I'd say you deserve much less than that. I would figure out what his % of total chips was, back that % out of the prize pool, then split the rest 50/50, or 40/60.