It takes about 5 minutes to change the battery, take it to your armourer who will have the battery for it.
I wouldnt pay more than £10 for it, they are prone to the spindles falling out.
Saying that mines been going fine for the last 8 years.
These watches were to replace the CWC watches but the army have gone back to CWC now. The Pulsar was a throw away watch. That is when the battery ran out it was replaced - the watch not the battery!
I have one sat in my desk which I have just had a look at. You may be able to get the back off and replace the battery but I'm not sure. It looks like it is not designed to have the back removed. By the way my watch is also a 04 and has been dead for a few years.
If it were me then I would not buy a Pulsar. If you simpley must have an issue watch then try and get hold of a CWC.
Hope this helps.
In that state - feck all to be honest! They are worth about £10 in good nick. That one looks like it's had a bit of moisture in it too. I'll have a look and see if I can 'find' one in better nick laying around.