I've used to always used consultants/agencies on the basis that while they cost a fortune, if the person you hired is not as good as their resume (and hey, that never happens does it?!?!) then you don't have to pay the fee and the agency is the one that wastes most of its time in finding someone to fit.

We then switched to Seek when it grew in popularity.

TBH the most success we've ever had with new people other than one brilliant receptionist through an agency was word of mouth. The industry I was in was so small, so you got to know everybody quite well and it was relatively easy to put the feelers out and occasionally poach ;-) Not sure if your industry lends itself to this though.

Good luck. I hope the process isn't too painful. I think getting good people is right up there as one of the hardest things about doing business.