My Google Fi is $20/m for connectivity and then $0.01/Mb until I hit 6Gb ($80) at which point everything after is no cost. Most of my data is on wifi, so my bill rarely goes above $25
I usually end up paying about $5/month, though that is a data only plan as I just use Google Voice for calls and use maybe a couple of gigs of data.
Having moved here from the UK where I was used to cheap mobile plans I just grate at how extortionate they are in the US.