We bought all our kit from CWG - do you have a branch near you (farm suppliers).
We've got about a 4 acre summer paddock which we strip graze to make sure they don't get too much at any one time.
We use the following:
a. An outdoor car type battery - the stockists will advise. We use an old one which doesn't hold its charge very well as a back up when re-charging the good one.
b. About 20 fence posts. We like the ones with lots of options on height.
c. A transformer (I guess this is the term) which has wires that go to the tape and clips that go to the battery and earth.
d. A metal stake which had little crosses to attach the wire clip to as an earthing post.
e. Some plastic screw eyes to attach the tape at the fence ends and to go round trees etc.
f. A gate thing which is a tape with a plastic handle which attaches to a wooden fence (to which we attach the end of the tape).
g. Loads of tape! You can either single or double it depending on how much you have an how far you want it to go. We double ours as the ponies could climb under otherwise.
h. We also bought a fence tester. Quite useful to make sure that all connections are working ok if you've a complicated set up like we have (round trees and at right angles etc).