I have no problem finding wine glasses at thrift stores. They may not be matching but that is part of the fun.
Socks, underwear, bras, swimsuits (maybe you can find them used but I don't want wear them).
I cannot wear used shoes, I need to buy new shoes and break them into my feet.
There was one year (maybe age 2-3?) I didn't have much luck finding clothes for my youngest. I am thinking because they are particularly messy during that time, and things that would normally be donated had stains, etc that made them un-donatable?
kids rain jackets. I need to get a waterproof rain jacket for myself as well.
Usually if trying to find a very particular house tool, will just buy new. Yes, maybe eventually find a drill or that rake, but the hassle is such better to buy new.
What I like to buy at thrift stores: glassware, books, wood furniture, shirts, cool lamps, vintage linens, items to make Halloween costumes out of ; ). I even scored a brand new velour house coat for my Mom. They looked like they were donated new, and it was the style she liked (zip up the front).