I see Hot Topic online has the 3 20" plushies for $39.99 (Twilight Sparkle, Pinkie Pie, Rainbow Dash; $10 more than Target.com), and I've seen in-store all 4 6" plushies for $8.50 (Twilight Sparkle, Pinkie Pie, Rainbow Dash, Fluttershy; $2.51 more than Target stores, $1.51 more than Toys R Us stores) and the 3 3" keychain plushies for $6.50 (Twilight Sparkle, Pinkie Pie, Rainbow Dash; haven't seen them anywhere else yet).
I checked about 6 local Walmart stores and haven't seen 10" plush Fluttershy yet.