I've just acquired Beogram 8000 with MMC 20CL cartridge for under $500. It was in a very good condition, probably as good as it could be considering the age. Beogram 4000 or 4002 would cost just as much, perhaps more due to the rarity. I think Clearaudio Emotion + Aurum would cost considerably more than Beogram, and it is not a fair comparison.
As far as the sound go, it's probably hit or miss as most B&O tables are very old and the condition will vary from one end of the spectrum to the other. MMC 20CL cartridges are superb, and they are probably as good as any $500 TT + cartridge combo. However I don't think the detail retrieval is as good as good MC cartridges.
I love my Beogram 8000. It is magnetic drive, and there is no motor or belt to worry about. The build quality is great, and the design is timeless after nearly 30 years. 4000 series is another timeless classic and I don't think you'll regret getting one.