I bought my 2000 LS 400 platinum edition on e-bay for $22,500 with 67K miles.Drove it for 3 1/2 years with no problems.I did put in a new battery and replaced the tires.
Also bought my 2006 LS430 with 9.9K miles for $47,500 on e-bay,so far no problems,except it seems to have tighter steering and the 18" wheels ride rougher than my 1993 and 2000 LS's.
However,I bought 2 2007 Toyota Highlanders on e-bay.One is fine,my girlfriend didn't like the looks of the rocker panels on the other.I took it to a body shop and was freaked by the 6 month wait and $7,650 bill.I was origionally quoted $1,500 and the further they went the worse it got,including air bags and headliner.
That being said,if you stick with an e-bay seller with high volume and almost 100% favorable{read the details}feedback you should be in good shape.The seller of the bad highlander had 100% favorable feedback,but only 43 items sold.I even gave him a favorable rating before discovering the problem.And of course after submitting,I couldn't change or add to it.
To me the difference in price between the dealer and e-bay is worth the risk.My local Toyota dealer wanted $10,000 more than I paid for each of the Highlanders.