Hmm, this one's tricky. Sort of. Couple of questions you should ask yourself:

1) Are you looking for a partner?

2) It's easy to get sold on a 'potential' amount. I mean, who wouldn't want $100k? Like you mentioned, you are at their mercy. If it fails, what have you risked? Most people ignore risk when you start throwing numbers out there.

3) If you had $100,000, would you invest it in this project/venture? And, with this person/individual?