I'm not as familiar with the GPLv3 but for v2 it's very clear that you're only allowed to charge what it cost you to provide the source code redistribution. Section 3 subsection b makes this very clear.

> Accompany it with a written offer, valid for at least three years, to give any third party, for a charge no more than your cost of physically performing source distribution, a complete machine-readable copy of the corresponding source code, to be distributed under the terms of Sections 1 and 2 above on a medium customarily used for software interchange;

I believe that "equivalent access" is intended to mean the more restrictive interpretation that you're not allowed to charge a fee for downloading the source code without also charging an additional fee for providing the binary to customers that already have a license. I.E. If you provide binaries for free on your website you can't pull a Mikrotik and demand that any requests for the source must be mailed in to an address in Latvia along with $50 (or something like that) for them to mail you a CD a month later while at the same time have binaries available on your website for free.

The spirit of that clause has always been that the distributor should not put some onerous burden on anyone requesting access to the source code. They can charge what it takes them to provide the service for GPLv2 and from what I can tell for GPLv3 it's limited to what they charge for binaries.

You don't have to rely on your beliefs for what "equivalent access" means. The writers of the GPL have already written a FAQ for what it means, which I linked to you above. They wrote this line knowing how most judges would interpret it. This is true for both GPLv2 and GPLv3.