Grow Lights for Indoor Seed Starting

One of the most popular seed starting questions I get from people interesting in growing from seed is whether they need grow lights when starting seeds indoors. The answer to that question depends on several factors. How many seeds are you trying to start? How much money can you invest in buying grow lights? Do you have any south-facing windows? Is your season long enough for direct seed sowing in the garden? The way I see it, buying grow lights for indoor seed starting is a luxury, not a necessity.