So given your budget, let's say about $200 for the gun and $100 for the tank & hopper.
Dynasty Ion Pro for $200
http://www.punisherspb.com/smart-parts-dynasty-ion-pro-paintball-gun-black.aspx
48ci/3000psi pure energy tank & Evlution 3 loader for $97.95.
http://www.punisherspb.com/electronic-loader-nitrogen-kit-black-evlution-3-48ci-hp-pure-energy-tank.aspx
Proto SLG basic for $200
http://www.paintballgateway.com/prslg09pagun2.html
Viewloader Evlution 3 for $60
http://www.paintballgateway.com/viev3molobl.html
OR Vlocity Jr for $80
http://www.paintballgateway.com/vilovljrbl.html
48ci/3000psi tank $30
http://www.paintballgateway.com/un48psialair.html
Electra 09 for $170
http://www.ansgear.com/08_Spyder_Electra_Paintball_Gun_p/kingmanspyderelecrta08black.htm
Cyclone 47ci/3000psi tank + Halo TSA Loader
http://www.ansgear.com/Cyclone_47_3000_HPA_Tank_Halo_TSA_Frontman_p/z473000hpahalotsafront.htm
OR Cyclone 47ci/3000psi tank + Halo B Loader + Rip Drive + Speedfeed for $109
http://www.ansgear.com/Cyclone_47_3000_HPA_Tank_Halo_B_Loader_Ripdrive_p/z473000hpahalob.htm
Evil Ion Kit for $270
Ion Marker
Choice of 62ci Guerilla Air or 48ci Pure Energy Tank 3000psi
Evil pipe Barrel kit (.686 .689 .692 backs) and choice of 2 tips
Choice of harnesses
3 paintball pods
Choice of loader (Evlution 3, Extreme Range overdrive sound loader, or Torque Loudmouth)
Tank Cover
Tank Dust Cover
http://www.firstcallpaintball.com/store/kits/3
Ion XE can be found for about $225 but that puts a tighter limit on the loader/tank. The XE is easier to service than the regular Ion so it's personal preference to go with that model over the regular Ion.
All the stores cited above offer free shipping over $100 so the packages should all qualify to save on that expense.