You can get a pair of the Infinity PRIMUS 360s for $400 on eBay.
http://www.stereophile.com/budgetcomponents/605infinity/index.html
http://www.hometheaterhifi.com/volume_10_4/infinity-primus-speakers-10-2003.html
http://search.ebay.com/search/search.dll?from=R40&satitle=PRIMUS+360

That is a pretty good speaker for that much money. Add an Infinity PS-12 subwoofer for $270 and they sound all that much better.
http://www.audioreview.com/cat/speakers/subwoofers/infinity-systems/PRD_172001_2741crx.aspx
http://search.ebay.com/search/search.dll?from=R40&satitle=PS-12

The Infinity Beta 50, which I just listened to last weekend, are surprisingly good for speakers that can be had for $750 a pair. They are significantly better than the Infinity PRIMUS 360. I can only compare the Infinity Beta 50s to the Wharfedale Diamond 8.3 and say that I thought the 8.3 was lacking in the low end bass compared to the Beta 50, but that shouldn't be a surprise. Vocals are something to behold from the 8.3s. However, the Beta 50s seemed to have more balance and transparency. I wish they had the Wharfedale Diamond 8.4, because it is for sure a better comparison within each product line.

Listen to both if you get a chance. You may like one over the other as I think they offer somewhat different presentation.

Otherwise, if you get a chance listen to the Meadowlark Swifts. Very easy to listen to.