I grow almost everything from seed, mainly because most of the things that I grow would not be found as plants anywhere around here (or most places, for that matter). Last season, I got some plants from Richter's Herbs, in Canada, but those are things that are not propagated from seed, and nobody around here would carry those varieties.
It was back in the 80s sometime when I started my seed program, and it was because a local nursery went out of business, and that was where I got my Ichiban eggplants, and a number of other unusual (back then) varieties, that the greenhouse lady would try out, and that's how I discovered them. I don't remember anything else that I started out with - just that Ichiban, that I had to have - or anything about the set-up, but it quickly snowballed. I used to start a lot more, but many of those were for friends, who are no longer in the area.