In my opinion, buying a seat of Rhino is well worth the cost. Considering that you can get it for less than $900 at online retailers, it will pay for itself very quickly in the time you save. Even with 2D drawings, there is a ton of interpretation when it gets to modeling it in 3D. With a 3D model, you are communicating your design intent MUCH more clearly, and that’s what it’s all about.
I work for a major toy company and use Rhino every day. I’ve used it to create countless models for building prototypes and for getting to engineers for communicating design intent. There is no other package out there that is as cost effective.
That said, if you had super-deep pockets, Solidworks is better for production stuff since the engineering can be done in the same package. With Rhino, my models always wind up being re-created in SW when it comes time for engineering. But they are both completely different kinds of programs, so you just need to figure out what suits your budget and work style the best.