I'd get a decent vac flask, a variety of filters, both qualitative, and quantitive, of differing micron size. Then a good buchner funnel/gasket for your flask. All this can be had under $40.
You could go for one of the kits with a plastic pump, but i'd recommend investing in a mityvac pump. If your not going to use the pump often, get the plastic one, but if your going to be using it alot, get a quality pump, i went through 3 plastic pumps before realizing that.