If you want a low cost spectrum analyzer (SA) that goes from a few kHz to 2 GHz. buy an SDRplay RSP1A SDR receiver for around $100 US. Then download the free Spectrum Analyzer program, written by a 3rd party, from the SDRplay downloads section. This program has a lot of standard SA features but you will need some good attenuators because the RSP1A needs to have a maximum signal input below 0 dBm.
Roger Need