I'm playing through the game a second time now and the first time I chose to hold off on paying him and I did a number of quests to power up a bit before moving on to the next chapter. Dont really know if it makes much difference but I thought that I'd be prepared just in case. Besides I figured that I'd make him sweat for his cash a little. This time I'll trying going the other route with the vamps and see what happens.
It's funny how the pesky vamps keeps pushing me to make a decision and Gaelen send his punk nephew to find me and try to convince me to follow him back to Gaelen's house. If I was playing an evil party I'd either Polymorph that kid or imprison him beneath the earth.
Eddith