Check first
THIS POST where there is a list of people who can help you unbrick/downgrade a PSP using Pandora. If you find somebody local contact them vis email or PM so you can meet locally.
The other option is to post your battery and stick to someone (ideally in your country) to get them both converted and returned back to you. It should not take over 5 days and is still cheaper than buying the battery anywhere else. Not to mention that you can only buy the battery without the files for the memory stick as the distribution of such files in the memory stick is illegal. So the posting option is still much better than buying cause your get all you need, and also produced legally.