Matthewsons have a few old Defenders in their November auction sale catalogue

There's a few series Landies but I can't see any Defenders. There's a rather dubious 1976 S3 109 hybrid on a Defender chassis. Tax and MOT exempt ! Wouldn't like to be stopped by VOSA in a spot check with that one as it'd probably be seized..............good luck proving it's a 109 - with Defender 110 chassis and axles. Should be a Q plate or none transferable reg.
Same goes for the 1971 88" coilsprung 200 Tdi hybrid.
Both of these vehicles could potentially be seized.
As for the estimates, this is what I would expect from genuine vehicle in decent condition, not a hybrid cobbled together from Defender underpinnings and Series body shell using original i.d's They are potential ringers as they are using the status of a vehicle that no longer exists to gain tax and MOT exempt status.Land Rover never produced a coil sprung 88 inch with Tdi engine in 1971, nor did they produce 109's on coilsprung chassis.
However, there are always exceptions to the rules. Hybrids built before a certain date , mostly on old classic RR chassis, or new 88", 109" coilsprung chassis bought by legit chassis making companies like Designa Chassis or Richards Chassis, but even then you still need to jump through hoops to retain an original reg.