Staking a friend

[waj4ever16]

I'm not exactly sure if this is called staking or buying a piece of someone but my friend is going to do a $400 tourney and asked me to put up at least $100 for him. I readily agreed because I am confident in his skills and feel that he will do pretty well. My question is: What percentage of his winnings (assuming that he makes the money) should I ask for? I remember a friend putting up $100 for me in a $320 tourney and since he was a nice guy and didn't really care for the c-note, he only asked for double his money if I made the money. What do you guys think? Thanks for your help.