Just a hunch, are they Sunglasses by any chance? 
I would recommend using design directories. Coroflot has a good one but you will also find a bunch of others online with a simple search.
I personally have never used sites that connect freelancers but if your project might be too small for a consultancy, that is not a bad route to go. Another way is check on Behance and contact designers directly who’s work you like and who are listing themselves as freelancer.
If you can’t afford to go to a consultant and have to find a freelancer, you will have to do a bit of detective work yourself to find a suitable partner.