After hearing some of Dennis's comments about inconsistency in performance of all AJ's Pioneers I would tend to shy away from these...
Cambrige Audio S-30 is a great choice, but its hard to buy now as it has been discontinued
Carnegie's would be great choice, but maybe a tad too much for this budget...
Option c) NHT's -
SuperZero 2.0 | Bookshelf Speakers | Premium Audio Equipment - at $60 I think these are no brainier to get
5x SubZeros = $300 w/ Free shipping
add HSU STF-2 for sub
Recommended Xover for these monitors should be around 100-110hz - you'd most likely will need to place the sub near the fronts
Result = stunning 5.1 for small to mid sized rooms