Big Bad Toy Store has the Dancing Groot on sale for $19.99 plus $4 shipping.
Alternatively, if you want to go with a more trusted chain, Best Buy has it on clearance for $24.99 with free shipping (but you'll need to pay tax most likely).
I missed on these when they were heavily discounted on the Frontpage several months back, so have been keeping an eye out on them. Not the best pricing they have ever been, but a decent discount if you don't want to keep waiting for a lower price.
"Experience the fun of Guardians of the Galaxy with this Hasbro dancing Groot toy. The battery-operated character shakes and dances while playing songs from the movie soundtrack. Groot also dances to external music, and his eyes light up for added effect. Delight a Guardians of the Galaxy fan with this Hasbro dancing Groot toy."