Looking at the current state of market, I have seen few very good companies assisting in appointment setting but unfortunately a number of new companies who have come into the market and have somewhat created a bad name of these so called "god ones". So your biggest challenge would be get hold of one and if you manage, its a win-win situation. If not, as rightly pointed out by others, it can go waste.
So decide wisely and do in-depth research to find your right partner.
The other way round is to hire a good resource and get hold of quality database, which I am sure can help.
Good Luck.