For even a moderate addict like me, there isn't enough room, time or money to start everything you can start right now. There are a slew of good seed companies who offer things you don't find as plants in most nurseries and big box stores. Everyone has favorite seed companies and seed varieties. You can google on seeds, check out garden watchdog for feedback on customer experience, and try searching this forum for Carolina Gardeners' favorites.

The vast majority of flower seeds that should be started in the house for best germination say 6 to 8 weeks before the last frost. I'm growing lady in red and coral nymph salvia, gruppenblau mealycup sage, vanilla ice gazania, coral flame new guinea impatiens, two types of dianthus, ... several more including perennials. Easy perennials include some of the nepetas, black-eyed susans, coneflowers, gaillardia, coreopsis. Tomatoes from seed are about the easiest thing there is. I went overboard this year on seeds and am as happy as can be thinking of spring as they germinate and grow. Also try the wintersowing forum for a solution to the space and lighting problem.

I winter sow all my seeds (not quite accurate: I also spring, summer, and fall sow). Hardy annuals can be winter sown right now as well as perennials and biennials. Winter sowing hardy annuals can be begun as early as December. Last year I planted out tiny seedlings of Clarkia and California poppies at the end of January. They were lovely.

Here is a link that might be useful: Winter Sowing FAQ's