I would have to see what they are capable of first, of course. Besides, it seems I don't have many options anyway.

You could also post here and select a few people who are interested to tell your idea to. The idea being you get them to sign/swear or similar not to divulge your idea or develop it without your permission. The only problem is if they say they already planned to develop something similar, but without any evidence to back that up, maybe you'd be in the right?

If that's an idea you like, I can promise faithfully to spend a few hours thinking your idea over and give you my thoughts on it, and not to discuss it with anyone without your express permission. I'm not sure how to make that binding without posting a leter to you, but maybe this post could be taken as such a 'contract'? PM me if you're interested.