"Most modern keyboards can't recreate that authentic, high-quality feel."

I would rather say that they can, but not at the $5 – $20 price point that many if not most modern keyboards sell at. Other gourmet keyboards like the Filco Majestouch and Das Keyboard go for ~$130. By that metric, used Model Ms and contemporary Customizers/Spacesavers from Unicomp (at $69: see http://www.pckeyboard.com ) are a bargain.