Right, PRISM is just the project that gives the NSA access to data stored on other (Google, Facebook et al.) servers. The active eavesdropping and other systems aren't included.
The data storage, processing, and development costs for the bulk of the programs that intercept/store the raw data are likely not included, either.
Based on the new slides[1] from WaPo, PRISM collection spans many other non-PRISM programs, such as the now-known MAINWAY (internet metadata), MARINA (internet content), and NUCLEON (voice content).
One of the fundamental issues with these discussions is that things such as what you're saying get thrown into the mix when we're talking about things we've actually seen evidence for.
We've, for a very long time, said things like, "this is probably happening". That is in no way whatsoever a novel idea. What is novel, and why these discussions are happening so frequently now, is that we have evidence that a 20mil/year program is actually happening.
So when we're talking about things we have evidence for, let's please avoid throwing in conjecture.