
It's getting really, really hard to find any cassette decks these days, let alone a decent one. The big names of old - Denon, Yamaha, Akai, Nakamichi - have all left the game and the one surviving model is a Sony TC-WE475 twin deck separates component... but you'll be hard pressed to find that on sale anywhere.
You might be best looking through the second-hand market. The Sony WM-D6C Pro Walkman was the best cassette portable recorder made, and - unlike the WM-D6 it replaced, was built up until about 2002, so you might be able to pick up a good 'un. Be very careful, though... the player could have been used as a bootlegger's toolkit and could be hammered. Spares and repairs are hard to come by, too.
Good luck...