I reckon $1-2 per month is way too low if they already have paying users at the $5 per month rate. ...but perhaps they could offer discounted pricing of say $4

I reckon $1-2 per month is way too low if they already have paying users at the $5 per month rate. ...but perhaps they could offer discounted pricing of say $4 per user if it was paid annually ($48/user/year instead of $5/user/month).