On 22/09/2015 19:21, Chris Hogg wrote:
On Tue, 22 Sep 2015 18:36:30 +0100, john west
wrote:

Would like to plant a couple of conference pear trees and a victoria
plum tree in large containers or similar with the possibility of
transporting them to somewhere else in a few years.

One trouble is that Plastic loft water storage tanks are so expensive.

Any ideas on what might be the best way of doing this please?

Have you considered a large blue plastic drum? Plenty on Ebay.
http://tinyurl.com/qbzetlz

Make sure you cut good drainage holes in the bottom.

Bear in mind that any container of the size appropriate to growing a
small tree in it for a few years will become very heavy.

I just wonder why?
if you are then going to plant them into open ground you would be better
with 2 or 3 year old trees when you have moved.
If they are going to stay in pots then look for dwarf patio trees they
will grow in smaller pots.
Though what you mean by "a few years" could be 2 or 3 years or 10+