I found a good discussion on another forum relating to your question, imsilly, and in it are mentioned a handful of converter options. They're specifically tackling the matter of Earthbound running on a PAL SNES. Take a look here:
http://fangamer.com/forum/Games/Moth...with-converter. The OP over there had success getting Earthbound to work, presumably free of frustrating save deletion, with the UA Universal Adapter Expert Version. So yeah, if you're seeing those on eBay, might be worth exploring.