If you can get a bargain then why not? But personally I would want it to be an absolute bargain (ie £15 or so) as you don't know what kind of life it's already had. Assuming it's running well and is a 1400W like the one in your link it should be good to work at 20ft.
Quite often you can put in a commision bid at an auction. Go to the viewing and give them your best price for what you want. If no one outbids you then it's yours, even if you're not there on the day.