Home Depot/Lowes bathroom plumbing fixures

I am hearing that Home depot and Lowes have different parts in their plumbing supplies compared to buying them in a plumbing store. We did ask someone that works in Home Depot and he did tell us that when he took his out at home and installed something from Home Depot, there was a plastic part compared to aluminum. Where have you bought your's? I found some things I like at Lowes and find nothing I particularly like in plumbing store. Not sure which way to go.

Home Depot/Lowes bathroom plumbing fixures

I bought all my bathroom fixtures at Blackman. I basically looked online at manufacturers like Kohler and Delta and then brought the product numbers in to Blackman and they helped me narrow it down.

Home Depot/Lowes do get things from major suppliers, but it is made differently, which is why they can sell it cheaper.