I've seen the sign-in at a couple of the nicer international lounges.

Generally, I think the intention is that the beer/wine prices are close to their regular bar prices. (That is, although hotel bar prices are notoriously high, I don't believe they intentionally mark C-lounge prices even higher than that.) The main difference is that the lounge is going to be just a few bottles - Heineken and Amstel seem near-universal plus a couple of that country's local macrobrews - whereas the lobby bar probably has a few beers on tap.

I'm not sure if they mark up wines to account for generous pours in the lounge.