Its always a risk, but I've done it a couple of times with no bad results 
First time was a Defender that looked good on ebay, and in truth, wasn't too bad, although I did wonder when the drivers door flew open at 60mph on the M621 as I wound the window up...... Turned out to be a good motor after sorting some niggly little things.
Second time was with a volvo V70 - bought from a volvo forum member who happened to be the head tech at a volvo garage, so good credentials
Excellent car, but going to give way to a Terrano.
I wonder if I'll be quite so lucky this time
First time was a Defender that looked good on ebay, and in truth, wasn't too bad, although I did wonder when the drivers door flew open at 60mph on the M621 as I wound the window up...... Turned out to be a good motor after sorting some niggly little things.
Second time was with a volvo V70 - bought from a volvo forum member who happened to be the head tech at a volvo garage, so good credentials
Excellent car, but going to give way to a Terrano.
I wonder if I'll be quite so lucky this time