"There's a shop near the south end of Tottenham Court Road (same side as the Dominion Theatre) that specialises in selling the one-or-two-generations-old sound equipment which the neighbouring stores no longer stock. I bought a portable CD player there a year or so ago, and I'd be surprised if they haven't still got some there today."

I just stopped by there an hour ago. The shop's called Hi-Fi Surplus, and I can confirm it has several models of CD Walkman in stock right now.