There's two types of RV antifreeze, the propylene glycol version and the ethanol (alcohol) version. One costs a lot more than the other.
The ethanol one will dry out seals in toilets and faucets, leave an offensive odor and taste in the water the next season, damage some anode rods, evaporate in toilet bowls and is flammable. The PG type will not do this.
The ethanol based RV antifreeze is significantly cheaper than the PG version and is what is readily available everywhere. PG based antifreeze can be hard to find and cost maybe around 50% more. I got a few jugs of them at a really good price last year at an independent RV repair shop. Also, sometimes you have to look closely at the label to see what the contents are.
If concerned about what you put into your potable water system, read the MSDS sheet for the specific brand & type of antifreeze.