We have bought lots of stuff from eBay, including the kitchen sink! Some items we buy are used, some new. Our stainless steel kitchen sink, sink hardware, and pot filler were new, and cost less and were better quality than offered at Lowes or Home Depot. We also bought our two bathroom vessel sinks and faucets new from there for at least 2/3 less the cost.
EBay is a great source for discontinued and nostalgic items. I've used it for replacing broken Corningware pieces, and a used iMac from a school system supplier.
I bought new, hard to find, specialized bowling balls for my grandsons, and new bowling ball bags.
Our biggest purchase was Hubby's fully equipped work van. We've had it for several years now. It was a great deal.
Just be sure to read the descriptions carefully, pay attention to the seller's feedback, research and compare the product from other sources, and ask questions of the seller when in doubt.