When talking about speakers, size of the room does not matter as much as distance from the speakers. Even if the room was 100' long, if you're only sitting 5' from the speaker, it doesn't require much to get you to reference levels. Highs and mids do not really need to pressurize the room to make their presence felt. Subs on the other hand are highly room size dependent if they are not placed nearfield.
That being said, I would second the recommendations for the Infinity Primus (P36x floorstanders to be exact). They retail for something like $300 each, but can be had for much less if you look around and are patient. I got mine for $108 each from Fry's when they went on sale a few months ago. Polk has the Monitor70 that looks very similar to the Infinity specs wise, but I've heard they have a little more emphasis on the highs. They are currently $220 each with free shipping at NewEgg, but the black is an additional $70 off if you can live with it. You'll have to order today as that promo code will expire though. They also have the Martin Logan Motion 10 for $130 each using the promo code (regularly $400). I have not heard this model, but I've heard their higher end models and they are some of the best I've heard.
Martin Logan Motion 10http://www.newegg.com/Product/Produc...82E16882981007
As a reference, I own a pair of Revel F52 and the Inifinities are right up there with them. Ok, maybe not that close, but MUCH closer to the Revels than most of the $2K - $3K speakers I auditioned. If I had to put a figure to it, they were perhaps 70% of the Revels at less than 1/30th the cost.
As for subs, the usual suspects are HSU and Epik. Can't lose with those at the budget you have. If you are handy with tools, you can probably do better for less if you DIY. This is when we will need to know about your room. You say it's about 2500 ft^3. That's not really that big if it's sealed. With the money you saved on the above speakers, a single Epik Empire or dual Legends should be plenty for that room. If it opens up to other areas that's when it gets a little dicey. I have a sealed 2300 ft^3 room and a single sealed 18" DIY sub is plenty for most peoples' tastes, but not mine
This brings up another question. How loud do you listen to your music and or movies?
Ok, I just reread your post. I thought you said you were going to spend an additional $800 on a sub. I take back the Epik Empire or dual Legend suggestions and recommend a single Legend or the HSU VTF-2 MK4 to get you within your budget if you get the speakers above on sale or find the older Infinity P361/P362 on sale somewhere. They are the same as the newer P363 other than cosmetic changes.
HSU VTF-2 MK4http://www.hsuresearch.com/products/vtf-2-mk4.html