My dad used to say, cheap merchadise is not good and good merchadise is not cheap.
I believe that a skimmer is one of the most important investments you can have for a marine aquarium and you get what you pay for.
If $$ is the issue, then go to the classifieds and get a 2nd hand unit dirt cheap that someone has outgrown. Then if you find the hobby interesting enough to stay in it, get a cadilac