I've only bought a few things on e-bay over the years, but my best purchase would have to be my poker set.  It's a 1000 piece 11.5g set with holographic denominations on all the chips and a nice carrying case.  I got it got $60 CAD, but $40 of that was the shipping due to the weight.  I have seen the same set in a few stores since and they are going for $180 to $220.  So I'd say that was a pretty good deal!