your local craigslist
You already posted it here so that's good.
If hiring an outside consultant is acceptable (since it appears to be contract based to start), you might want to see what hits you can get on elance.com as well.
Thank you Mike.
Not trying to start an HR discussion here, but I see this so much I feel the need to comment. By specifying WHERE and WHEN the work needs to be performed, you flirt with the line of contractor vs employee. I recommend reviewing the guidelines (or talking with your HR department) about federal laws of contractor vs. employee.
"The general rule is that an individual is an independent contractor if the payer has the right to control or direct only the result of the work and not what will be done and how it will be done.
You are not an independent contractor if you perform services that can be controlled by an employer (what will be done and how it will be done). This applies even if you are given freedom of action. What matters is that the employer has the legal right to control the details of how the services are performed."