Whatman is definitely the cheapest way to go; and even though there are other ways, let's admit it -- most of us are too cheap to spend any extra on newer filtration methods... heck, we do it ourselves to save as much dough as possible in the first place. However, there are other options which do work, and they are as follows:
1) Millipore 40mm centrifuge vacuum units -- used in conjunction with whatman prefilters, these vacuum units are a delightful alternative to syringe filtration. It takes awhile, but your hands do not hurt like h***. They work great for 50-200ml
2) All-glass filtration setups, various -- I sell more all-glass setups than I do anything else. They work flawlessly, and the only drawback (if you consider it so) is they have to be cleaned and sterilized every filtration cycle. They sterilize with filter in place, in a sterilization pouch, after the unit is cleaned.
3) Millipore 73mm steritops -- although they only last 1-4 hours and use polystyrenes, as long as you keep your usage to within this parameter there have been no complaints on the nearly 200 I've gotten rid of. They are useful up to 1000ml with the .45um filter unit, but really are not a good idea to use, IMO; you have to use glass lower units, however, as the plastic lower units don't hold up.
4) Millipore hi-cap 10cm2 filters -- filter 3-4X faster than the whatmans, but the filtration media blows at 45psi. They work well once you figure out bursting pressure, though, but are fairly expensive for the luer-lock version. Here is the thread for the Invalid Link Removed, and I will update that thread in a few days.
5) Stainless steel pressure units -- these units are the cadillac of flat membrane filtration (at least for what we can afford; there are some really nice dedicated filtration units of different sorts out there but...), and filter a full scale of magnitude faster than comparable glass units. $$$
New test samples will be sent to mods shortly to re-test filtration capabilities of the disposable units. They will let you know what works and what is crap.
