i paid £5500 for my td5 1999 T reg hardtop but thats on 154000 miles and of good condition
you dont say what type of td5 is it a pick up, station wagon, hard top as all attract different values the station wagon being most desirable so most expensive
if this helps,
for a 300tdi 1998 90 county hard top with excellent chassis, good inside and out, 120,000 on't clock, NO service history, I paid £6500.
could have maybe got it for £6250