Forum member Zeya informs us that Toys R Us now has LEGO Series 6 Minifigures instock. Unforunately, it has been marked up to $3.5 (MSRP: $2.99) like the other Series Minifigures. The good news is that right now there is no limit on them and if you spend $50 or more on LEGO, you can get $10 off. So if you buy 15 minifigures, you can get them $2.83 each which works out to be roughly 6% off.
They also have LEGO Series 4 and Series 5 still instock. Spend $75 and your order will qualify for free shipping as well.