In terms of adult size, hardiness, price and availability, The Russian Tortoise is probably your best bet. These show up regularly at pet shops and are always available from dealers. They are relatively cold tolerant and usually thrive with good care. The truly small tortoises are very delicate and expensive. Sulcata tortoises are relativly hardy, very personable and inexpensive, but many owners are dismayed by their rapid growth and huge adult size. Leopards are intermediate in size and hardiness and are readily avilable as captive bred animals.