Hi all...I didn't do a search to see if it was already mentioned in here, but 'Pixia' is a really decent FREEWARE image editing program that allows layering, and (I believe) will also save in a PSD format. Anyhow, for those unaware, here's the link to 'Pixia'.
http://www.ne.jp/asahi/mighty/knight/
EDIT: Sorry, not sure how to make the address 'Linky' and not just a line to try to copy and paste.