The expense in FCC testing comes from many repeated trips back-and-forth to a certified test lab because your product has emissions problems. The idea is to know your emissions well enough ahead of time so you pass the first time at the lab.
For FCC testing in-house, do a search for FCC "pre compliance testing". There is a category of lower cost test equipment with features that allows a company to check their product somewhat accurately as an aid to product development and to reduce the risk of failure once you visit a certified FCC lab. Of course, any test results are non-official.
Agilent/Keysight sells some of their lower cost spectrum analyzers with a EMI/quasi-peak detector option. This is meant to process/detect signals similar to the expensive EMC receivers used by a professional lab. Companies developing products with intentional radiators (transmitters) will buy a GTEM Cell which is far less expensive than a anecoic chamber/room. Depending upon your product, how it is powered, and it's size, the list of equipment you might want to consider varies.
But, of course, you need engineers sharp enough to know some RF and to know the limitations of equipment in order to get reasonable test results and have confidence in what your are measuring.