The price for my help is...

Do not deal with the fae.

Their values are incomprehensible and prices disproportionate. Their bargains are vague, riddled with loopholes, and held to the exact letter of the agreement, spirit be damned. Their power lets them claim the otherwise inviolable intrinsic properties of things, so with an incautious word you can accidentally barter away shards of your selfhood. And you're not getting them back.

Do not deal with the fae. It's folklore rule number one.

So when your players decide to deal with the fae, here's a d30 list to decide what it will cost them. I tried to leave each item vague enough to allow for classic loophole/"exact words" shenanigans from both sides, and to give hasty adventurers plenty of opportunities to doom themselves. If your players are clever, they might come out unscathed, maybe even better off. If they rush headlong into a deal without taking the time to determine exactly what they're promising, hit them with the full fairy tale treatment. Each possible result has a range of interpretations from whimsically innocent to horrifically inhuman.

The price for my help is...

1) A memory (happy, painful, inspirational, formative, childhood, forgotten)

2) A name (of my own, yours, your enemy's, my enemy's, your love's, a stranger's, a hero's, a god's)

3) A favor (small, large, specific, unspecified)

4) A dream

5) A surprise

6) A gift

7) An answer

8) A child

9) Your opinion

10) Your cooperation

11) Your company

12) Drink with me

13) Join me for a meal

14) Accept this small token…

15) Carry a message to…

16) Bring me…

17) Find (someone, something, a place, information)

18) Entertainment (riddle, song, story, game, wager, dance, combat, hunt)

19) What's most important

20) What's least important

21) Praise

22) Service (day, month, year, unspecified)

23) TEETH

24) BLOOD

25) HAIR

26) EYES

27) BONE

28) HEART

29) LIVER

30) Kill...