If you need to build a pair of speakers in the $400.00 range, I suggest limiting your choices to the Studio Series one π, two π or two π tower speakers.If you have $400.00 to spend on each speaker, then I'd also consider any of the Thermionic Series models, or the Theater Series four π or seven π Speakers. The Thermionic Series four's and seven's are probably too large, but the Theater Series four π and seven π Speakers and the Thermionic three's would probably suit you just fine.
Look around on this forum a litle bit and you'll see a lot of discussions and feedback about each of these speakers. Any of them should work well for you.