Target Active Tennis Racquet 27"
Also available for the same price in 21" 23" 25".
In-store says $10 scans as $5.
Plenty available in Hornsby Target.
(If you need balls Kmart has a bit better deal than Target at 15 for $10
http://www.kmart.com.au/product/15-pack-tennis-balls/122340)
Extra Info
CAUTION: Do not aim at head, eyes or face.
So where should I aim to ensure one shot kill?