I bought a tiny one going cheap at Lidl (or somewhere) a few years ago. It lives in the garden, spends 3 weeks in an overheated classroom and then 2 weeks in the house. It suffers a bit from the heating but recovers well over the summer. It is now 3 feet tall. I repot it every so often but will probably leave it now as I want to be able to still transport it to and from school.
We've just got a 5ft one from an independent tree farm. It needed repotting straight away. They said to increase the pot by at least 2 litres a year and it should grow just under a foot a year. After 2-3 years, put it in the ground.