you could use google sketchup! It's a GREAT program and there are some tutorials for it. It would make your tank 3D!

Brand new the ER-RS80 is 225 off their site's pricing www.euro-reef.com

You may want to try an octopus skimmer, I have yet to see a bad review on them... Keep your eyes peeled for something used if you are on a budget, that's your best bet.