Where can I buy cheap tortoises?
from a pet shop?
You might be able to get a tortoise from any of the local aquariums at a decent price, but certainly not for cheap. You can also order the tortoises from online stores like www.reptilesncritters.com/tortoises.php and www.turtlesale.com/home/.
I had 5 of them that I got at a gas station for 10 dollars but they are 100 dollars for 1 at a pet store so check out markets and other small places like that
Adopt one! Go to www.Petfinder.com, and find adoptable tortoises near you!