Have you done the modifications to the Coralife yet? I use one on my 240g tank. I have a different pump, 750gph, and mesh modified, works alot better than the original set up. You could buy one of the other skimmer pumps to make it a better skimmer also.
But all be told, the ones with the best LH/Intake and using a bubble plate work the best. They are basically all the same, fine the one that fits your budget, with the best air intake and utilizes a bubble plate, you can't go wrong. But you do want it twice rated for your tank volume.
You should be looking at the NAC 8 though.
Curve 7 would be a good option
But to get at the price you want, then your only choice that would really get you close to what you need is the SCA-302 $179
SCA-302 180 gallon Protein Skimmer