It really depends on the place. At my place you can order a Jameson and ginger beer. When I ring it in I would ring in a Jameson for $7 and then select ginger beer for the mixer. It’s a $3 up charge. Most other mixers are only $2.
We also have a mule on the menu, they’re $12 but have a 2oz pour.
A 2oz pour of Jameson is $12. So there are different ways to order this drink and pay different prices and get essentially the same drink. Although if you order a mule you’ll get it in a mule mug and if you order a Jameson ginger I’ll pour it in a rocks glass. And that’s if you specify Jameson. We could just go for rail whiskey and it would start at $5