I'd consider Totem Sttaf's - which can be found used at the upper part of your price range. They image like there's no tomorrow. The only concern I may have is with a room that large they may thin out.
As for the GMA Europas - I agree with Evita - I had a pair, and they're great, but IMO may get lost in a room that large.
The Sttafs have enough low end - nearly as much as the Vandersteen 2s - to be worth considering. The added advantage of the Totems is they have a small footprint and are really easy to place. OTOH, if you can't place them 4 ft from the wall you'll lose a lot of that great imaging.
As for the GMA Europas - I agree with Evita - I had a pair, and they're great, but IMO may get lost in a room that large.
The Sttafs have enough low end - nearly as much as the Vandersteen 2s - to be worth considering. The added advantage of the Totems is they have a small footprint and are really easy to place. OTOH, if you can't place them 4 ft from the wall you'll lose a lot of that great imaging.