According to ride magazine you can pick these up for as little as £650, but at that price it would be a high mileage shed. Anything worth owning is going to set you back at least £1200 and it will most likely have at least 25000 miles on the clock and be far from mint.
Ride will tell you that they never caught on in the UK, but they were popular enough to be manufactured from 1995 up until the present day (now a TDM 900) and I knew what they were even as a zitty teenager. Mainly because I had a mate with a TDR250 and there was the odd TDR125 kicking about at the time.
Even so the TDM850 proved more popular than the smaller TDR’s and the Yamaha TRX850 sports bike which had the TDM engine (albeit with a different firing order) so I’d say that it was a fair success. I had a few copies of Used Bike Guide where they often got a mention as they could often keep up with the sportsbikes of the day.
The upright riding position is ace for seeing over the traffic and drivers always seem less likely to pull out in front of taller bikes. If it rides anything like my Kawasaki Versys it should be pretty manageable in heavy traffic allowing you to pick your way through. Should be a pretty good tourer too with a comfy riding position and big cc’s. Stick on some supermoto boots for a bit of leg out action and I recon it would scratch pretty well around tight corners.
If you could get one as cheap as Ride magazine says then I would say it is a definitely a bargain, however I haven’t seen a cheap one for a very long time and you could get newer lower mileage bikes for the same money.