Upload & Sell: Off
I check out ebay for good pricing, sometimes there are some really good auctions. I also follow certain products before and after a retail product purchase. Case in point the 100L IS Macro.
Both on ebay and here on FM used 100s go for 800 to about 825; plus shipping/PP fees. An ebay auction just ended on a plus 1 yr old warranty-less 100L, it sold at 810, 12 for shipping without insurance, 25 for both...so 835 if you played it safe...that's been the norm since release. I bought mine late last year at B&H for 899 with it's 1yr warranty, no shipping/tax charged, waited a week for delivery.
That extra 64 bucks was worth every penny, just for possible return alone. As Peter noted, this 50 f1.0 is a no-return auction, personally I never e-bay unless the return window is 7 days or more from date of receipt, you have to inspect, use what you purchase and have time to meet the return deadline. The risk of loss is just to high when flying blind, few pictures on the internet are not proof of anything, product in hand is.
I've had decent luck getting gear form local estate sales, out of 30 or so purchases on ebay only two went sour and paypal recovered my funds...fortunately I'm on a low budget, don't buy high priced items, only once going over the 1k mark.
With a rare, potentially high priced product like this 50 f1.0, with no return options, highly risky in my book...lots or research with the seller is required, emails sent back n forth are manditory, be a pest, they make for great evidence if a fraud occurs. If a seller won't openly talk about the item...no sale...even if I really want it