I got one of the recent Jouef TGV releases. It's near Rapido quality (not sure on how prototype specific), has sound, and was flippin expensive to try to recreate a full rake.
The four car base set was $370 USD.
Each add on car was $45 USD, and you need six to get to a full rake. So you're looking at $700 USD for Jouef quality. I can't imagine what a detailed Rapido TGV would cost.