How about an eshopps skimmer? they have a small foot print and work pretty well. The Curve that X posted is also an awesome skimmer too, just more than your budget.
This is one item that you really shouldnt skimp on, it will be the lifeblood of your filtration. Buy one that is quality the first time around, trust me, not worth getting a seaclone or anything like that and then having to get a more expensive one down the road.
If you have to, do massive water changes for an extra month or so while you save for the more expensive skimmer.