I have found some interesting things on ebay, too ! I now buy most of my garden seeds and plants from ebay, and I can find a lot of interesting things that regular seed catalogs do not carry. Even on items that are in regular seed catalogs, such as strawberries, can often be found in greater variety and for better prices than anywhere else.
Back in the day (when I was a herbalist), I also ran a seed-finders service. Never made much money, but it was okay as part-time income, so that is maybe something one with knowledge of botany, latin nomenclature, internet search skill, and a lot of spare time could operate.