The Beomaster and Beolab are well worth having restored - many of us have done just this and Classic Audio, run by Frede, specialises in exactly this.
You did however ask what these are worth. In non working order, very little - tens of pounds. A fully restored and certified pair will cost many hundreds. Whether it is worth this is clearly debatable. One does not see restored vwersions appearing on the market as on the whole they are restored to order and those ordering them would never part with them! You will find many owners will have the very top of the range modern equipment but keep a Beolab 5000 system as well.
The Beomaster 5000 is a broadcast quality tuner and the Beolab is an amplifier that is still well worth listening to with plenty of power. You could do with a better turntable though - B&O did supply a couple of decks to match the system - confusingly both were called the Beogram 3000, and even more confusingly, neither were fully B&O products!