Any ideas on the best way to save a single value (text value) in NetSuite that can be accessed & changed via scripts that are installed from multiple different bundles? This value should also be copied from prod to sb when a refresh is done. I would like to avoid storing this in a custom record if possible. I also do not want to have to install a separate bundle to create this central location to store the value. Thinking a custom company preference might be best?

company preference isnt likely to be a choice unless those bundles all share a script

Yeah, not sure if that's even possible

Any script, regardless of the source bundle, can access the value of any script parameter (which is what I'm assuming you're referring to when you say "custom company preference"). However it's not possible to set/update the value of a script parameter via script. I don't think you have any choice but to use a custom record unfortunately :(