I saw some 8-pounder balls at Champs at Scarborough Town Centre last weekend. Not cheap though -- approx. $55.00.
Also saw some at "Play It Again Sports" in my area -- but they only had 10 and 12 pounders and once again not cheap -- approx. $65.00. These did not look "used" though.
Since dumbbells are an option to the balls (as will be demonstrated in the new videos), I'm going to try those first. If I'm not satisfied or feel I'm missing out on some of the benefits, I'll get the medicine ball.
Patricia