Tell them you'll do it for $49,900 and they have a deal.
Demo means they've beat the shit out of it for 5,000 miles most likely.
I've seen what they do to demos
'12 CLS550 Palladium Silver - loaded
'11 E92 M3 ZCP - SG/B-EXT/CF, M-DCT, loaded
'11 E93 328i, BSM over Saddle Brown, sport, loaded
'08 550i M-Sport, Carbon Black (Gone but not forgotten), '06 W211 E55 AMG (Gone, miss this animal),'01 E39 540i Sport