Welcome aboard, Jean. Importing and exporting firearms-related parts is tricky as the parts may fall under the International Traffic in Arms Regulations
(ITAR) umbrella. I believe that I cannot mail you a basic Model 8 wood fore-end or simple butt-plate without facing felony charges for exporing firearms parts. You would likely have to consult a licensed exporter/importer to handle the transaction if you do find the magazine parts you're looking for. Sorry to be a killjoy, but that's the world we live in.
To be honest, the magazine follower and spring could likely be fabricated with minimal fuss, especially if the original pieces were in suitable condition to use as a template.
I look forward to pictures of a rare FN 1900 with some "character."
