I skimmed the thread and may have missed some stuff so dont flame me.
TANK AND STAND:
have you checked out craigslist for tanks?
Build a stand yourself?
You can def cut alot of costs if you build a stand and canopy yourself with just a lil elbow grease. I can help you with designs for one if you want. I did build the one below and this was about 2 weeks ago, since then the polyurethane has cured and color fully soaked in and looks better than this pic.
Since you want to do a discus tank, they like tall whispy vegetation from what i have read and like to swim through it. I would do the long version of the tank, most plants will fit more than easily at that depth and you can manipulate everything easily that way.
LIGHTING:
Lighting, you can get a 72 inch fixture, the Nova Extreme Pro Saltwater. Now it may be a saltwater fixture because ity comes with the actinics, but you can switch those bulbs out and make it a fw fixture and have 3wpg. Its a $729 fixture, but its 72 inch, perfect fit, t5ho, 3wpg and your tank is 150ish gallons, so it kinda fits the bill.
http://www.drsfostersmith.com/product/prod_display.cfm?c=3578+3733+13822+18700&pcatid=18700
FILTERS:
I would build a wetdry for this setup. You have a large tank and a wet/dry would probably be beneficial in your situation. Im not the person to talk to about for wet/dry as i have never done it but i have done alot of reading it on it. Canisters will work well for you too. Eheim makes a rock solid product has i have heard it quoted in the past as being a workhorse, the classis series to be specfic. The eheim 2028 looks like it would work for you but the only advanacements i see between that and the 2217 is the selfpriming and the extra half gallon or so capacity. The 2217 is the classic, you need to prime it but you have 1.5 gallon media capacity and higher flowrate. You could get 2 2217 for the price of one 2028. I would do the 2217 just for the customizability and larger media capacity. The flowrate on canisters is always slower, but supposed to have higher filtration. I would still go wet/dry though if it were up to me.