Depends upon the country.
If you are in the UK, then Wembley Loudspeakers will do them, expect to pay around £100 all in, they've done a couple of difficult ones for me, a pair of Type K woofers and a pair of Type S woofers - both with full paper cones.
(PS I am very proud of the Type S as they are rare in the UK and they turned out well)
The Beovox 4700 will be easier to do, make sure to get them done in rubber and not in foam. Whilst you are at it, it would pay you to replace the crossover capacitors - get yourself bi-polar electrolytics,or you can purchase solid state capacitors but this can be expensive depending upon how many you need.
s it worth it - in terms of pure economics, probaly not, you could spend the sme on somthing like a pair of S120s and these would give you a better pair of speakers, however you would pay much more to start off with. Does anyone repair old B&O stuff based on cold hard logic instead of the vintage restorers lossmaking emotion?