At $80 MMultiAnalyzer is the least-expensive one I know of with all those features. Blue Cat's multi-channel version of FreqAnalyst is a hundred bucks. Flux's is $600 (!).
MAnalyzer is not a mulit-channel analyzer, but it's pretty good and includes an R128 loudness meter and sonogram. I don't know what's different between the free and paid versions. Voxengo SPAN remains my favorite single-channel spectrum analyzer.
One alternative to MMultiAnalyzer would be Voxengo GlissEQ. It's only 20 bucks more and you not only get the multi-channel monitoring but also have a decent equalizer too. You don't have to just look at the spectra, with GlissEQ you can actually do something about it.