Absolutely not. There must be a zero-fee option to encourage the flow of open source hardware from students and hobbyists.
Trying to impose fees on a commercial organisation goes against the OSHWA definition. Not to mention that OSHWA is happening all over the world. Are you ready to assume global responsibility in many different legal jurisdictions?
However For a commercial organisation that wants to use an external independent certification body, it should be possible for an external body to perform this. We should end up with a open source model that allows a host of certification bodies to handle this. These could be asked to be trained/certified by the OSHWA (do we have people able to do this?). For end users using an independent certification service, at best, any fees could take into account the complexity of the product.
After all, an open source aircraft or car would be more complicated to certify than an open source shoe.