Bulk 3D Modeling of Rings

I need a 3D modeler to produce a large quantity of ring models. This will be a continued project, with a requirement for 30-50 designs each month. The designs will be basic in detail, focussed on shape and proportion rather than intricate details. I'll provide a general reference as a guide for each model. Ideally, you should be experienced in jewelry modeling, understand standard jewelery proportions and able to deliver in the .obj file format. My budget is set at $5 per model.