It seems the market isn't sure what these cars are worth. There are S4's going for around £6000 (even some with lowish miles) all the way up to the £11,795 example where the seller must want to keep it.
1999 AUDI S4 S4 Quattro 4dr Saloon (private)
Manual, 110,000 miles, Imola yellow,PAS,trip computer,Drivers airbag,Passenger airbag,Side airbags, ABS,4 new tyres,fsh,full electrics, full leather,no trouble codes,comes with memoscan vag5053 fault scann
£5,800
1999 AUDI S4 S4 Quattro 4dr Saloon (trade)
Manual, 72,000 miles, Red, 2.7 Twin turbo 270 BHP Full leather RCL EW AW FSH Totally standard Good T&T Immaculate condition. P/x considered.
www.carlwilliams.co.uk.
£5,999
1998 AUDI S4 Quattro Twin (trade)
Turbo Saloon, 1998, 101000 Miles, FRSH, Blue, half leather, Blue suede trim, alloys, climate, 6 speed Manual, very rare car, excellent condition, drives superb.
£6,495. ono.
2000 W Reg AUDI S4 Quattro (trade)
4 Doors, Manual, Saloon, Petrol, 87,000 miles, Imola yellow. Full leather interior, xenon lights, Bose sound system, ESP Stability control, ABS, Adjustable seats, Adjustable steering column/wheel
£8,000
All the way up to these 2 at much higher prices
2000 AUDI S4 S4 Quattro 4dr Saloon (private)
Manual, 54,000 miles, 54000 miles, Bi-turbo yellow, with gunmetal 19 inch MTM wheels & chassis, Movit brakes & Milltek exhaust, carbon & black interior, kept covered, not used for commuting and
£10,900
2000 AUDI S4 S4 Quattro 4dr Saloon (trade)
Manual, 64,500 miles, Laser Red, X REG,2001 MODEL FACELIFT,MANUAL, 2.7 BI TURBO V6,GENUINE UNMODIFIED STANDARD CAR,64500MLS FASH + ALL MOTS,JUST SERVICED 10-11-2007 @ AUDI DEALER,LASER RED
£11,795