The reality is, of course there is somebody out there, and somebody else is going to find them and make a fee. In this situation, you need a robust set of exhaustive activities which increases your chances of finding some one.
Here's my top ten activities for finding additional candidates
Return the placements you have made in this area recently call them , ask them who they know it's fits your spec, they are on the ground in the right market/geography, there is a strong chance they will know some one and they should be motivated to help you.
Change your search criteria, for example go much further back in time. People who were looking 2/3 years ago tend to go in cycles, and some will, by chance be looking again.
Set up a reward scheme for referrals. This is offered by many recruitment agencies and uses the people on the ground in the thick of it, the reward you pay will always be less than your reward. Vouchers tend to best for tax reasons, try £250 worth of vouchers, speak to your boss about it. You can build up a network of referrers which can be highly effective.
find another recruitment agency who has a candidate and split the fee.. 50% of a fee is better than no fee at all! Building a small network of agency suppliers you can improve your number of placements. These fees are at 50%, but in most situation it would be nothing without it. This is also good for your standing with the client, providing a better service.
Look for free trials on job sites with a CV search facility. This may seem like a long shot, but there are frequently free trials on offer and you only need one good candidate to make your fee.
Run a 'database maintenance' exercise. Run your search criteria for all time and call everyone on the basis of just wanting to update the database on people current position. Be careful here as these people may not have approached you recently. If they get grumpy and ask to be removed, be polite and do so, and mail them to confirm this.
Head hunt. Check this with your recruitment manager, some people are strictly recruitment and no head hunting. However, when you have a fee of several 1000 in potential, it's very tempting. If don discretely and properly it can produce excellent results.