I'm interested in finding this out as well. I am currently in the process of planning a bathroom remodel. I have found more of what I'm looking for on Wayfair, but I've also seen quite a few reviews that have countertops that arrive broken as well as warped drawers and other damage.

I've purchased 2 vanities from Wayfair. They both had marble countertops. One was perfect. The other had a pretty backsplash piece that was broken in 2, and some damage to the paint finish on the bottom side. Wayfair requested pictures and then offered a new vanity, a replacement or a discount. I took the discount. I don't remember how much of a discount, but they were very fast replying and very accommodating. My contractor touched up the paint and when the back splash piece was installed the crack was not noticeable. The vanities were beautiful, but I think the quality was in line with the prices.

I do like the return policy at Costco, though. I've never had any bad experiences returning an item there. I just haven't seen a vanity that I really like for my bathroom remodel, otherwise, I'd probably buy one from there.

Wayfair is just a website store which sells stuff from a variety of manufacturers so the quality would vary.

Customer service depends on Wayfair and when I bought a headboard from them, I found their customer service to be fairly good. In my case, they had just left the boxes in my building lobby instead of taking them up in the elevator. Since I had paid a significant amount for delivery including using their "putting it together service" I had expected that their freight service could take the five minutes to bring it up in my elevator, I had to pay a guy from my building staff to bring it up for me and Wayfair gave me a refund for about $100 which was the amount I then paid to my guy. I thought it was more than fair since I could have gotten someone to bring it up for less - but I was happy to pass along the windfall to the guy from my building.

That said, I personally would NOT buy anything heavy or bulky through the internet because the logistics of a return would not be something I would want to deal with. Obviously people do take the risk but I just wouldn't want to do it. When I remodeled, I had a custom hood fabricated and it had to be returned. It was completely the company's error and it was handled by my designer so I didn't have to pack it up and shipping was paid by the company and I didn't have to repack it. By I couldn't imagine handling this on my own. Also costs for sending it back are buyer's responsibility unless there is some kind of product defect.

I also bought a medium size chest from an independent company and the door fell off after a week of use. They wanted me to ship it back to them but the logistics of attempting to find packing material - pack it up - arrange for pick up - and then have them quibble with whether it was defective or whatever was ridiculous. I filed a claim with my credit card company and ultimately the credit card company decided in my favor but it could have gone the other way since the issue was whether I should go through the incredible hassle of sending back what was a damaged piece of large furniture. If I had bought locally, they would have just sent someone to pick it up and it would have been over.

I can not speak for Costco, but Wayfair is great, we are also listed on there, but here on Houzz too. For the size you are after, that is about the price range.