I don't think you will find authentic Oakley lenses, you could post in the forums WTB. Otherwise there are aftermarket lenses from Fuze lenses or seek optics. But if you looking to sell you might find that the price of new lenses might be more than what you would be able to sell the frames for....
On eBay you’ll find many aftermarket brands. Just know you pay for what you get. Go cheap and that’s what’s you’ll get. I buy Linegear, Fuse, and Ikons mostly.