Quadramac,

Since you have internet access, why not download the free Stuffit Expander version 5?

Here's one place to get it:

http://68kmacdownloads.googlepages.com/home

I'm guessing that the .bin file format it's in can be decoded and decompressed by your existing Stuffit Expander version 4. If not, do a Google search for Stuffit Expander 5 (or "Aladdin Expander 5" as it was called later) - you're almost certain to find it downloadable in a Self-extracting archive or similar format that you can use.