I will caution to to avoid freelance sites for EE projects
- You don't have a clear chain as far as IP goes if you go for any kind of patent (though, not likely in your case), but I'm citing general practice.
- Its dubious that the freelancer will be around to help you get whatever certifications are needed for your product (FCC or otherwise)
- What / who will be checking their designs?
The consensus for your question on Chip Hacker was to approach a local university, which is a good idea in some cases. I've done the same ... sometimes it works, sometimes not. As mentioned in answers there, I had major problems getting a device through certifications (We were making some USB gizmos).
If its really this basic, you may want to just shop around for some smaller EE firms and get some ball park quotes. You know your IP is going to be respected if you stay in your country, you get a guarantee of certification and govt approval .. and you have a much lower risk of a grad student flaking out on you :)