Hi,
Does anyone know if there something like 99 Designs except for Product design as opposed to logos/websites?
While the bulk of the contests held are for logos and web designs, 99designs hosts contests to meet just about any design need. If by product design you mean a product label or box design, that would be placed in the print design category. Any type of product prototyping (creating custom product container shapes/packages, etc.) or anything else not fitting one of their categories would most likely go under other graphic design.
here’s their example page of label/product designs…
http://99designs.com/label-design
Yes, try quirky | social product development - they’ve successful developed quite a few real-world products.