As with anything, its usually better to buy things that are of name brand because they are proven to work. Then again, you can many times get cheaper things to work.
In question about that memory, they are that cheap because they are double density chips. Some motherboards support double density, others dont, especially older mobos. Many manufactureres wont mention if their mobos support double density or not, but a rule of the thumb, and a good one at that, is that if your mobo can support up to 1gig or more of memory, then it can support double density memory, which is what most 512 chips are (correct me if Im wrong in the 512 thing). If it cant support that much, then its likely, although not for sure, that it doesnt support double density. If anything, call the manufacturer and make sure.
my two beaver pelts.
(Ive looked into this alot. My mobo has one of these chips and runs just fine.)