If you don’t need to be able to browse in person, ChemGlass is our go to for lab grade glassware for work. Out of curiosity why is vacuum filtration your only option? Alternatively it looks like you can get a cheap vacuum filtration setup on Amazon for like $50 This claims it’s a Büchner funnel but it’s not, it’s a fritted disk filter which can be more annoying to clean depending on what your filtering out and how big/small the particles are

https://a.co/d/d0vJv2c