I'd suggest looking at the normal suggestion system in Core and see what the runs would be according to those guidelines. Then like half the nuyen for really quick ones, and consider raising it relatively for really complicated things.
Iirc, if you just abduct someone you likely face what, dicepool <12, no real big dangers? That'd be a 9k-base, ~10.5k after really good negotiation, in the base system. If it's a simplistic run of maybe 3 scenes instead of 6, make it 5k?
You could even have some adventures PROMISE the original amount but due to circumstances/liars it becomes the new one...