The standard size for a bag of coffee is 12oz, at least in the US. $20/lb is equivalent to $15/12oz. $15 for a 12oz bag of coffee is pretty standard for anything that isn't bottom rung these days. It's not even 'great' coffee at that price; I'm just talking about something mid-tier like Counter Culture coffee which is available nationwide.
Anything cheaper than that and you are firmly into the budget coffee tiers.
Anything cheaper than that and you are firmly into the budget coffee tiers.