Need Help picking windows in MD/DC

[ghujks]

I need 20 windows replaced that qualify for the tax credit, and I don't want to spend over 10k for them. So far, I'm leaning towards:
vytex double heritage = U val .28= $368/win
vytex triple heritage = U val .24 = $525/win
vista constant force triad 7 (also a triple)= U val .23 = $450/win
Okna (haven't gotten quote yet, but somewhere in high $500s I suspect - although did get a quote from a shady dealer for $400)

I've also gotten quotes which I ruled out from:
Thermal Industries (TI) triple 1 coating, gold = U val .26 = $566/win
Metal Industries (MI) xact 1650 = U val .29= $526/win
Champion = U val .28 = $582/win
Simonton = U val .3 = $600/win
Alside Excaliber II = U val .3 = $335/win
vytex great view = U val .27 = $535/win - this one charges an additional assumed lead price of 120/window

Any advice? Thanks.