A design classic that doesn't come cheap. But if you do want to invest in a 1960s Dieter Rams-designed Braun RT-20 radio, this one on eBay could be worth checking out.
It's a tabletop tube radio, said to be in 'perfect vintage cosmetic condition' and able to tune into LW, MW, and UKW (FM) signals. Of course, it's a desirable and influential design too, the work of Dieter Rams and Hans Gugelot, complete with a white enamel on metal face plate, beech veneer body and distinctive controls. There's also an iPod / MP3 adapter included, so you can play digital music through this vintage radio too.
Want it? You'll be looking at £790.32 for a 'Buy It Now'. Pricey, but this has got to be an appreciating classic.