Amazon has Marvel Legends Series Mjolnir Electronic Hammer, for $79.99 with free shipping.
1:1 full scale 19.75-inch premium role play hammer
Authentically designed wrist strap and pommel
Voice-activated light features reveal the symbol of Odin
Premium detailing and finish
Includes Mjolnir electronic hammer and instructions
x3 1.5v AA alkaline batteries required (not included)
Alternatively, the same can be bought from Toys'RUS with free shipping at the same price.